Hobbies Calculators

Find the near limit, far limit and total depth of field for any lens, aperture and focus distance — plus the hyperfocal distance for your sensor.

Convert aperture, shutter speed and ISO into a single exposure value (EV) — and see the lighting condition it corresponds to.

Find the longest exposure that keeps stars as points, not trails, using the accurate NPF rule — and compare it with the older 500 rule.

Plan a time-lapse: how many frames to shoot, how long to run the camera, and how much card space you need for a target clip length.

Check whether your fish tank is understocked, balanced or overstocked using the inch-per-gallon guideline, with remaining capacity in inches.

Score a 10-pin bowling game frame by frame: type the balls (X for a strike, / for a spare, - for a miss) to get every frame score, the running total, the maximum score still possible, strike and spare stats, and series totals with handicap. A quick estimate from strike and spare counts is included too.

Estimate a mature horse's weight from heart girth and body length using the standard weight-tape formula, in both pounds and kilograms.

See your new Elo rating after a game: the expected score from the rating gap, the points won or lost, and how the K-factor scales it.

Judge a D&D 5e combat encounter's difficulty: apply the monster-count multiplier and compare the adjusted XP to your party's thresholds.

Calculate guitar string tension in pounds, kilograms and newtons from the gauge and string type or the unit weight, the scale length and the tuned note — for one string or a whole set in any tuning, or find the gauge that gives the tension you want.

Turn a tempo in BPM into note delay times in milliseconds — quarter, eighth, sixteenth, dotted and triplet values for delay and reverb.

Work out how much fertilizer to spread to hit a target nitrogen rate, and see the phosphorus and potassium you apply along with it.

From your last frost date, find when to sow seeds indoors and when to transplant seedlings outside — with the countdown to last frost.

Work out what a resin 3D print really costs — resin by weight, electricity, IPA wash and consumables — with a full per-print cost breakdown.

Find exactly how much fragrance oil to add to your wax for a target scent load — in ounces and grams — with a note if you exceed the safe maximum.

Calculate how much epoxy resin your mold needs by shape and dimensions, add a waste allowance, and split it into Part A and Part B by mix ratio.

Swap the yarn in any pattern: enter the yardage required and your substitute's yards per skein to find how many skeins to buy and your leftover.

Scale a cosplay armor or foam pattern to your body: enter the designer's height and yours to get the exact print/resize percentage and piece sizes.

Work out your dog's daily raw (BARF) food portion from body weight and activity, then split it into the 80/10/5/5 muscle, bone, liver and organ ratio.

Find the right prey weight and feeder-rodent size for your pet snake from its body weight, plus a feeding-frequency guide by size.

Calculate dry KNO3 and KH2PO4 doses for the Estimative Index (EI) fertilizer method from your planted-tank volume, per dose and per week.

Size a backyard chicken coop and run from your flock size, breed (or a mixed flock with bantams) and whether birds free-range or stay in — with suggested dimensions, nesting boxes, roost length, ventilation, daily feed and water, and a check of how many birds an existing coop and run can hold.

Estimate exactly how much yarn a knitting project needs from a small gauge swatch — total yards, metres and the number of skeins to buy, with a waste margin.

Turn your crochet gauge swatch into the exact stitch and row counts for any finished size — chain length, stitches per row and rows to work.

Exact dice odds for any NdS roll: the chance the total is exactly, at least, at most or between targets, with a modifier, D&D advantage or disadvantage, keep-highest or keep-lowest (4d6 drop lowest), rerolls, and counting successes in a dice pool — plus the full distribution table and chart, mean and standard deviation.

Work out the experience points needed to reach your next level or a target level on a custom XP curve — plus XP for the next level and levels remaining.

Choose the aperture you need for a wanted depth of field: enter focal length, subject distance and the sharp zone you want, and get the f-stop to set.

See the net exposure change in stops when you move aperture, shutter speed and ISO from one setting to another — brighter or darker, and by how much.

Calculate an aquarium's water volume in gallons and litres from its dimensions — rectangular or cylinder — with a realistic allowance for substrate and décor.

Resize an image or video without distortion: enter the original dimensions and a new width to get the matching height, the simplified ratio and the new megapixels.

Find the plain-steel string gauge that gives the tension you want at a given note and scale length — the reverse of a tension calculator, for building custom string sets.

Build a race pace band: enter your goal finish time and distance to get your pace per km and mile plus the cumulative split time at every marker.

See how many rating points a game will win or lose: enter your rating, your opponent's rating, the result and your K-factor to get the exact Elo change and new rating.

Mix model or airbrush paint to an exact ratio: enter the parts and total volume to get millilitres and drops of each component, with the ratio simplified.

Convert 3D printer filament weight into length (and cost) from the spool diameter and material density — know how much of a spool a print actually used.

Add up the real cost of an FDM print: filament, electricity and machine wear from the grams, print hours and your energy rate.

Work out the resin cost of an MSLA print and split it across the models on the plate — from millilitres used and your bottle price.

Enter each player’s final score to find the winner, the winning margin and the average — a quick end-of-game tally for up to four players.

Score a Magic: The Gathering deck’s mana curve — average mana value, land ratio and a recommended land count from your spell counts.

Turn the pot and the bet you face into pot odds — the ratio, the equity you need, your real chance of hitting from your outs, the expected value of calling, the implied odds you would need, plus minimum defense frequency and rake.

Convert your number of outs into the exact chance of hitting on the turn, the river or by the river — with the classic rule of 4 and 2 for comparison.

Enter your remaining score and get a valid 1–3 dart checkout route that finishes on a double — the standard finishes for 501 and 301.

Turn your league average into a handicap — the bonus pins that level the field — from your league’s basis score and percentage.

Calculate your Surface Air Consumption from a dive: gas used, depth and time give the cu ft/min you breathe at the surface — the basis for planning air.

Find a telescope-and-eyepiece combination’s magnification, true field of view and exit pupil — and check it against the scope’s maximum useful power.

Estimate a drone’s flight time from its battery capacity, usable charge and average current draw — plus the pack’s power delivery.

Work out how much fabric to buy for a set of quilt pieces — how many fit across the fabric width and how many yards you need.

Turn a stitch count and fabric count into the finished design size and the fabric size to cut, with margin included.

Estimate how much wax and fragrance oil a batch of container candles needs, and how many wicks to buy.

Estimate the sodium hydroxide (NaOH) and water for a single-oil cold-process soap batch using saponification values and a superfat.

Calculate the alcohol by volume, apparent attenuation and gravity drop of a homebrew from its original and final gravity.

Estimate a wine’s alcohol by volume from its starting and finishing specific gravity, plus the potential alcohol of the must.

Work out how much honey a mead batch needs to hit a target starting gravity, plus the estimated maximum alcohol.

Predict roasted coffee weight from green weight and roast loss, or find the loss percentage that describes your roast level.

Correct a long film exposure for reciprocity failure using the Schwarzschild exponent for popular black-and-white films.

Find the key your open chord shapes actually sound in with a capo on any fret — and see the transposition per semitone.

Convert a tempo in BPM into the length of every note value in milliseconds, with dotted and triplet timings for delays.

Turn your gauge swatch and a target width into the number of stitches to cast on, and rows to knit for a given length.

Size the aquarium heater you need from your tank volume and how far you have to raise the water above room temperature — with the next standard heater size to buy.

Get a safe starting CO2 injection rate in bubbles per second and per minute for a planted aquarium, based on tank volume and how heavily planted it is.

Estimate how many fish your freshwater tank can hold using the classic inch-per-gallon rule, adjusted for fish size, plus a rough count for a chosen adult length.

Estimate the PAR reaching your corals at depth from the fixture output at the surface and the water column, and see which coral types suit that light level.

Work out how much birdseed your feeders use, how long a fill and a bag last, and how often you will refill, from feeder capacity and daily consumption.

Size a coop and run for your flock from the number of birds and their breed size, with recommended interior area, outdoor run area and nesting boxes.

Estimate a season’s honey harvest from your hives, honey supers and frames, with the total in pounds, gallons and the number of jars you can fill.

Size a compost bin from your weekly kitchen scraps and yard waste and how long material sits, with the volume in cubic feet and a suggested cube dimension.

Estimate a model rocket’s peak altitude from motor thrust, burn time and rocket mass using a simple drag-free two-phase model — an optimistic upper bound.

Convert your RC car’s real speed into its full-size scale speed for any scale (1:5 to 1:87). Enter a measured speed, time a run over a known distance, or estimate top speed from motor kV, battery, gearing and tyre size. Results in mph, km/h and m/s, with the realistic-looking (Froude) speed, a scale chart and a pinion gearing table.

Find the hyperfocal distance for your lens and aperture — the focus point that keeps everything from half that distance to infinity acceptably sharp.

Find the longest shutter time before stars trail on an untracked shot using the 500 rule, adjusted for your crop factor and a stricter 400 or 300 variant.

Add seam allowance to your finished dimensions and find the total fabric length you need to cut a set of panels — including a waste margin.

Estimate how much embroidery thread a design needs from its stitch count and average stitch length, with skeins and a waste margin.

Work out how much clay to weigh out for a thrown cylinder or bowl from its height, diameter and wall thickness — before and after firing shrinkage.

Calculate the resin volume and weight a mold needs from its shape and size, with a top-up margin so you never mix a short batch.

Split a total batch of epoxy into resin and hardener by any mix ratio — by weight or by volume — so every pour cures hard.

Estimate how much wood stain to buy for a project from its surface area, the number of coats and the coverage rate on the can.

Find the total length of molding to buy for a picture frame, allowing for the rabbet, mitre corners and cutting waste.

Estimate the total wire a jewelry project needs — for wrapped loops, coils or a repeated element — with a working-tail allowance.

Convert your pattern pieces into the leather hide area you need to buy, in square feet, with a nesting-waste allowance for irregular hides.

Find how many beads fill a given length from their size, and how many you need for a whole strand or project with a spare margin.

Plan a scrapbook or photo album: turn your photo count and photos per page into pages, two-sided sheets, page protectors, albums needed, cardstock to buy and how thick the finished album will be.

Estimate how many drills (round or square) a diamond painting canvas uses from its size and drill dimension, plus bags to buy.

Turn any tempo into delay and reverb times in milliseconds — quarter, eighth, sixteenth, dotted and triplet values, so your effects lock to the beat.

Find the exact frequency in hertz of any musical note from A440 tuning — pick a note and octave and get its pitch, MIDI number and period.

Move a frequency up or down by any number of semitones and see the new pitch, the exact frequency ratio and the interval in cents.

Transpose any note up or down by a number of semitones and get the new note name, octave, frequency, interval and cents, plus a whole chord progression transposed in sharps or flats, for capos, key changes and vocal ranges.

Convert a number of bars into seconds for any time signature and tempo — know exactly how long an intro, loop or section will run.

Estimate a track’s running time from its tempo, time signature and bar count — add up intro, verses and choruses to hit a target duration.

See the click interval in milliseconds for any tempo and subdivision (eighths, triplets, sixteenths, quintuplets, sextuplets, septuplets and thirty-seconds), the equivalent subdivided BPM to set on a plain metronome, the bar length, and swung-eighth timings.

Compute the fundamental pitch of a vibrating string from its length, tension and mass using Mersenne’s law — and see the nearest musical note.

Find the exact distance from the nut to any fret, the spacing from the previous fret and the length left to the bridge for any scale length, in mm and inches, with presets for guitar, bass, ukulele, mandolin and banjo and a full fret-slot table for building or refretting a fingerboard.

Add sound levels the right way — combine up to four decibel sources on an energy basis to get the true total level for mixing and noise work.

Estimate the size of an uncompressed WAV or PCM recording from its sample rate, bit depth, channel count and length — plus the data rate in kbps.

Change a tempo by a percentage to get the new BPM, the resulting track duration and the pitch shift in semitones if tempo and pitch are linked.

Adjust your flat-ground pace for a route's elevation gain using Naismith's rule to get a realistic hilly finish time.

Combine a cache's difficulty and terrain stars into a single planning score and read what the pairing means for your day out.

Spread your weekly mileage across a shoe rotation and see how long each pair lasts before it hits its replacement limit.

Convert a chainring and cog combination into gear inches and development to compare gearing across any bike.

Estimate front and rear tire pressure from your total system weight and tire width for a comfortable, low-rolling-resistance ride.

Work out how high your kite is flying from your line length and line angle, and how much line a target altitude needs.

Convert real-world dimensions to any model railway scale — and back — across HO, N, O, G and more.

Compute an RC airplane's wing loading from weight and wing area to judge whether it will float or fly hot.

Estimate how many paintball shots you get from a CO2 tank of a given size, plus refills for a full day of play.

Convert airsoft muzzle velocity (fps or m/s) and BB weight into joules — or a joule limit into the highest fps for any BB — with the same-energy fps on 0.20 g and heavier BBs, a check against typical US, UK or European field limits by role (CQB, rifle, DMR, sniper) including minimum engagement distances, and a BB-weight table.

Estimate how many distinct lines an opening repertoire holds from its branching factor and depth in moves.

Turn a puzzle's given-clue count and the hardest technique it needs into a simple difficulty score and band.

Estimate what a trading card collection is worth: split bulk, mid-value and chase cards, apply a condition factor, add graded slabs, then see what you would net after eBay or TCGplayer fees, a store buylist offer, shipping and what you paid.

Calculate the intrinsic silver or gold melt value of coins from their weight, fineness and the current spot price.

Work out how many album pages and binders a stamp collection needs from the number of stamps and stamps per page.

Estimate a comic's value at a target CGC grade by scaling a reference near-mint price with a standard grade multiplier.

Find a LEGO set's price per piece in cents and see how it compares to the roughly 10-cents-a-brick rule of thumb.

Estimate the linear shelf space a board game collection needs and how many shelves it takes when boxes are stored spine-out.

See how long it will take to clear your gaming backlog from the number of games, average length and hours you play each week.

Chance of pulling a featured unit (or several copies) in N gacha pulls at a flat rate, with an optional spark or exchange: pulls for 50%, 90%, 99% or your own target, expected pulls and copies, the guarantee point, premium currency and cash still needed, and the full copy-count distribution.

Expected value of a loot box, case, pack or crate from its drop chances and item values — three quick tiers or your own full drop table — compared with the price plus any key cost, after marketplace fees. Shows the house edge, the spread per box, what N boxes cost and return, the chance of at least one rare and of breaking even, boxes and money per rare, a pity guarantee and the rare value needed to break even.

Compare two speedrun times to see the seconds saved, the percentage improvement and your new pace relative to a target.

Compute a build's damage per second from hit damage, attack speed and crit, then see the effective damage after mitigation.

For dice-pool RPGs, find the chance of scoring at least one success and the expected number of successes when rolling a handful of dice.

Estimate how much food to pack per day for a backpacking trip from your target calorie density and trip length.

Estimate how much water to carry per day on a hike from duration, intensity and temperature.

Separate your pack’s base weight from consumables and see your total and skin-out load for lightweight backpacking.

Find the realistic sleeping capacity of a tent from its floor area, using per-person space you choose.

Estimate the sleeping-bag comfort rating you need from the coldest night you expect and your cold tolerance.

Calculate the structural ridgeline length for a camping hammock to set a repeatable, comfortable sag.

Estimate how much firewood you need for an evening campfire from burn time and fire size.

Build a trail mix and see its total calories and protein, carbs and fat per serving.

Choose the right hydration reservoir size for your outing from duration, effort and heat.

Find your ideal trekking pole length from your height, with adjustments for climbing and descending.

Estimate calories burned on a hike from distance, elevation gain, pack weight and body weight.

Estimate how much sunscreen a full day outdoors uses, including reapplication, and whether a bottle will last.

Turn a board’s thickness, width and length into board feet and total cost — the volume unit lumberyards actually price by.

Convert linear feet of a known-size board into board feet — and compare a per-linear-foot price against a per-board-foot price.

Estimate how much a board will expand or shrink across its width with a seasonal change in moisture content, using species dimensional-change coefficients.

Predict how much a loaded shelf will deflect in the middle from its span, thickness, width, load and material — with a pass/fail against the L/360 rule.

Get proportioned mortise-and-tenon dimensions — tenon thickness, shoulder size, width and recommended depth — from your stock thickness and rail width.

Lay out evenly spaced through dovetails: enter board width, number of tails and pin size to get tail width, pitch and the half-pins at each end.

Work out how much oil, poly, lacquer or stain you need for a project — from surface area, number of coats and the finish’s spread rate.

Size a panel glue-up: how much wood glue the joints need and how many clamps to space evenly along the boards for even pressure.

Build a sensible sanding schedule from a starting grit to a final grit without skipping steps — never jumping more than about 50% at a time.

Find the airflow (CFM) a duct delivers at a given capture velocity, and check it against the minimum CFM your machine needs.

See how many pieces you get from a board once the saw kerf is subtracted, how much material the cuts eat, and what’s left over.

Pick the right pocket-hole screw length, drill-guide and collar settings, and thread type from your material thickness and species.

Estimate the weight of a fish from its length and girth so you can release it fast without a scale.

Estimate how deep a lead-core trolling rig runs from the colors out and your speed, or how many colors you need to reach a target depth, with speed in mph, km/h or knots, a depth-by-colors table and a setting you can calibrate to your sonar.

Estimate how heavy a sinker you need to hold bottom in current, based on water depth and current speed.

Get a recommended leader length for your technique and water clarity, from fly fishing to spinning rigs.

Look up the AFFTA standard grain weight and tolerance for any fly line weight, in grains and grams.

Estimate how much fishing line a reel spool holds, in yards and meters: from the spool’s flange, arbor and width, or by converting the reel’s rated capacity (for example 12 lb / 250 yd) to a different mono, fluorocarbon or braid diameter, with backing, fill gap and a capacity table for common lines.

Estimate how much chum to bring for a fishing trip from hours on the water, current and how many lines you run.

Estimate how much live or cut bait to buy per angler per day from group size, hours and how the fish are biting.

Get a simple solunar fishing rating for any date from the moon phase, with major and minor period guidance.

Find the right rod power rating for your target from your line test and lure weight, from ultralight to heavy.

Check whether your load fits your kayak, using the usable-capacity rule that keeps a boat stable and dry.

Estimate how many koi or goldfish a garden pond can hold from its volume, using safe per-fish water rules.

Turn a flash guide number into a real working distance and the aperture you need — with an ISO adjustment for the light you actually have.

See what focal length your lens really behaves like on a crop sensor — plus the equivalent aperture for depth of field.

Work out the horizontal, vertical and diagonal angle of view for any lens and sensor — and how wide a scene it covers at a given distance.

Find the largest sharp print your camera can make — pixel dimensions and print size at any DPI, from megapixels and aspect ratio.

Plan a time-lapse: how many frames you will shoot, how long the finished clip runs, and the interval needed to hit a target length.

Turn a bitrate and clip length into a file size, find the highest bitrate that fits a card, disc or size limit, or see how long you can record — with codec presets, audio tracks, container overhead, GiB sizes, card tables and upload time.

Count the frames and drawings an animation needs from its length, a SMPTE timecode or a frame count, at any frame rate including 23.976 and 29.97 drop-frame — on ones, twos, threes, fours or a mix, with holds, key poses, timecode, seconds+frames, 35 mm feet+frames, and drawing and render time estimates.

Screw on a neutral-density filter and get the new shutter speed instantly — with the stops, ND number and optical density it costs you.

Meter-free daylight exposure: the Sunny 16 rule gives you a shutter speed for any ISO, aperture and sky condition.

Convert an exposure value (EV) into a real shutter speed for your chosen aperture and ISO — plus the approximate scene brightness in lux.

Estimate the memory cards and backup space a shoot needs from your shot count and average file size — RAW, JPEG or both.

Convert Kelvin to mireds and find the mired shift a warming or cooling filter needs to move one light source to another.

Measure a ring you already own and get the US ring size, ISO (circumference) size and matching diameter — from either the inside diameter or the circumference.

Work out the melt value of scrap or broken gold from its karat, weight and the live gold spot price — and see what a refiner payout percentage leaves you.

Estimate the melt value of sterling, coin, Britannia or fine silver from its weight in grams, troy ounces, pennyweights or kilos, its fineness and the silver price you enter — with a buyer payout percentage, fees, a mixed-lot list, offer check and price tables.

Estimate the carat weight of a mounted or loose gemstone from its length, width and depth using shape factors and the stone’s specific gravity.

Get a rough diamond price from the 4Cs — carat, cut, colour and clarity — by scaling a base price per carat with quality multipliers.

Find how much alloy to add to reduce a piece of gold to a lower karat, keeping the pure-gold content fixed — the standard karating-down calculation.

Work out how many beads you need to fill a strand of a given length from the bead diameter and any spacer gap, with an overage cushion.

Convert an AWG wire gauge to its diameter in millimetres and inches and cross-sectional area, with typical jewellery uses for each gauge.

Standard finished lengths for collar, choker, princess, matinee, opera, rope, men’s chains, bracelets and anklets, how many links your chain needs from the link size (allowing for the clasp), the closest store length, and how far it hangs from your neck size.

Estimate the length and weight of sizing metal needed to size a ring up (or removed sizing it down) from the size change, band width and thickness.

Plan a hand-knotted pearl strand: how many pearls fit a length, how many knots you will tie, and how much thread to cut.

Convert the weight of a wax model into the weight of metal needed to cast it, using specific gravity — plus an allowance for the sprue and button.

Find the total binding length, number of cross-grain strips and fabric yardage to bind a quilt of any size.

Calculate quilt backing yardage including overhang and the number of fabric widths you must seam together.

Estimate how many yards of fabric a dress needs by style and size, adjusted for 45-inch or 60-inch goods.

Work out curtain yardage when a patterned fabric must repeat and match across every drop.

Choose the right pillow insert size for a cover so it looks plump, and get the fabric cut size for the cover.

Estimate how many fat quarters a quilt top needs from its finished size and a cutting-waste allowance.

Find the cut square size and number of squares to make any count of half-square triangles at a finished size.

Find the strip width and size of the fabric square needed to make continuous bias tape of any length.

Cut elastic to the right length for a waistband: inches off or a percentage of your waist, joining overlap, casing or band size for your elastic width, a hip stretch check for pull-on garments and how much elastic to buy.

Match your opening to the nearest standard zipper length for garments, pillows, cushions and bags.

Estimate the thread a sewing project consumes and how many cones to buy for lockstitch, serger and coverstitch seams.

Buy enough fabric to survive pre-washing by adding a shrinkage allowance to the length and width you need.

Build a balanced D&D 5e combat encounter by turning your party size and level into easy, medium, hard and deadly XP budgets.

Work out a D&D 5e character’s hit points at any level from hit die, Constitution modifier or score, fixed average or rolled HP, up to three multiclass classes, Tough and other per-level bonuses — with a level-by-level table, the chance that rolling beats the average, Hit Dice and short-rest healing.

Estimate how long it takes to paint an army of tabletop miniatures and how many hobby sessions you will need.

Work out exactly how much thinner to add to hobby acrylic paint for brush or airbrush work, in drops and millilitres.

Find the maximum safe current a LiPo battery can deliver from its capacity and C rating, and the C rating your motor draw needs.

Plan a drone mapping flight: turn altitude, camera specs, forward and side overlap into ground sampling distance, footprint, photo spacing, shutter interval, flight-line spacing, photo count, flight time and motion blur.

Estimate the usable wind range for a kite of a given size and rider weight, so you know when a kite is underpowered or overpowered.

Turn track length and car speed into lap time, scale speed and how many laps fit in a timed slot-car race.

Project your final pinball score from your pace so far, see the points each remaining ball must add to beat a high score or replay value, with extra balls, a back-loaded scoring option and a ball-by-ball plan.

Check your land or resource ratio for a trading card deck: expected lands per opening hand and the odds of a keepable hand.

Find the average, minimum, maximum, standard deviation and exact odds of any dice roll like 3d6+2, 4d6 drop lowest or a d20 with advantage, with a full probability table and chart.

Estimate the finished size of a jigsaw puzzle from its piece count and how big a table or board you need to build it.

How much priming sugar to bottle-condition beer to a target CO₂ volume — corn sugar, table sugar, DME, honey, candi syrup and 12 more — by beer style, corrected for the beer’s temperature and residual CO₂, in litres or gallons, with per-bottle doses and bottle pressure.

Regulator pressure to force-carbonate a keg to a target CO₂ volume at your fridge temperature — set-and-forget PSI, burst-carbonation shortcut, and the serving-line length to balance it.

Correct a specific gravity reading taken at any temperature to the hydrometer’s calibration temperature (15.6 °C / 60 °F or 20 °C) — for accurate OG, FG and ABV in brewing and winemaking.

Convert °Brix or °Plato to specific gravity and back with the ASBC polynomial, the Lincoln (BYO) equation or the 4-points rule — plus Oechsle, Baumé, sugar in g/L and potential alcohol. Correct a refractometer reading on wort with your wort correction factor, or work out that factor from a hydrometer reading.

Correct a refractometer Brix reading taken during or after fermentation for the alcohol present. Start from the original Brix or a hydrometer OG, choose the Terrill cubic or linear correction, and get the true final gravity, ABV (standard and high-gravity formulas), ABW, apparent and real attenuation, your wort correction factor and a reading-by-reading table and chart.

Potential ABV from the starting gravity, Brix or Baumé of a must, juice or wort — fermented dry or to a chosen final gravity — by the standard, alternative, Hall, Balling and winemaker formulas, with hydrometer temperature correction, refractometer final readings, sugar added later, attenuation, calories and an ABV-by-final-gravity table.

Apparent attenuation from original and final gravity, real attenuation and real extract corrected for alcohol, ABV and calories — compare with your yeast strain’s published range.

International Bitterness Units for up to four hop additions with the Tinseth formula — alpha acid, weight, boil time, batch size and boil gravity — plus the Rager estimate and bitterness ratio.

Predict beer colour in SRM and EBC from up to five grains — weight and Lovibond — using the Morey equation, with MCU, colour name and style range.

Temperature to heat your strike water so the mash lands at the target — Palmer’s infusion equation from grain weight, grain temperature and mash thickness (or a total water volume), with mash-tun heat loss as a fixed allowance or worked out from the tun’s weight and material. In °C or °F, kg or lb, litres, quarts or gallons, with mash volume, first runnings, a mash-out infusion and how much hot or cold water fixes a miss.

Volume of boiling water to raise a mash from one rest temperature to the next — protein rest to saccharification, or saccharification to mash-out — from grain weight and current water volume.

Total brewing water, strike and sparge volumes from batch size, grain weight, boil-off, grain absorption, trub and equipment losses — for batch, fly and no-sparge brewing.

Predict post-boil gravity and volume from pre-boil gravity, volume and boil-off rate — or the water to add / extra boil time needed to hit a target OG.

Yeast cells needed for a batch from volume, gravity and style (0.75 / 1.0 / 1.5 million cells per mL per °Plato) — with viability by pack age, packs required and whether a starter is needed.

Size a yeast starter — DME and water for a 1.036 starter wort, expected cell growth on a stir plate, shaken or still — to reach the cells your batch needs from one pack.

Adjust the hop weight when substituting a variety or crop year with a different alpha acid percentage to keep the same bitterness — with hop storage (age) alpha-acid loss.

Blend two worts, beers or wines of different gravity or ABV to a target — Pearson square proportions — or dilute a strong wort with water to a target gravity and volume.

How much sugar to add to a must, juice or mead to reach a target Brix, specific gravity or potential alcohol, by exact mass balance. Table sugar, dextrose, honey, grape concentrate or your own syrup, in grams, kilograms, pounds and cups, with the new volume, a staged-addition table, and the water needed if you want to lower the Brix instead.

Free SO₂ target from wine pH (0.5 or 0.8 mg/L molecular), the addition needed in mg/L, and the amount of potassium metabisulfite powder, Campden tablets or 10% solution for your volume.

Grams of tartaric acid or acid blend to raise titratable acidity to a target — or potassium bicarbonate / calcium carbonate to lower it — with the expected pH shift.

How much water to add to bring a spirit down to bottling strength, using ethanol-water density tables for volume contraction (or the simple ratio). Also: the strength after adding a set amount of water, the spirit needed for a batch, alcoholmeter temperature correction, % ABV or US/UK proof, water by volume and by weight, staged cuts and bottle counts.

Convert alcohol by volume to US proof (ABV × 2), old UK Sikes proof (ABV × 1.75), French Gay-Lussac degrees and alcohol by weight, or any of them back to ABV. Also shows pure alcohol per bottle, standard drinks per bottle and per serving for five countries, and US proof gallons.

How many bottles a batch fills — 330 mL, 500 mL, 750 mL, 12 oz, 22 oz bombers, swing-tops or kegs — allowing for trub and bottling losses, plus caps, sugar and labels to prepare.

Shooting interval, number of frames and recording time for a time-lapse — from event duration, desired clip length and frame rate — with memory card size and recommended intervals by subject.

Convert shutter angle to shutter speed for any frame rate (180° rule = 1/(2 × fps)) — cinematic motion blur at 24, 25, 30, 60 and 120 fps — with flicker-safe speeds for 50 Hz and 60 Hz lighting.

How many frames a stitched panorama needs — from focal length, sensor size, orientation, overlap and the horizontal and vertical field to cover — with the per-frame field of view and final resolution.

Convert illuminance in lux or foot-candles to exposure value (EV at ISO 100 and at your ISO), or EV back to lux. Get the shutter speed at your aperture, the ISO needed for a hand-held shutter speed, a full equivalent-exposure table and an EV-to-lux chart, using the incident-meter constant C = 250.

How many trees fit in a field or orchard from row and in-row spacing (square, rectangular or triangular layout) — trees per acre and hectare, rows and trees per row, and the spacing needed for a target density.

Expected harvest from fruit trees by species, rootstock size and age — kilograms per tree and per acre, years to first crop, and how much to plant for a family or a market stall.

How many seeds or plants to sow for a bed or row from area, plant spacing and germination rate — with packets required, seeds per gram, and square-foot gardening equivalents.

How much garden lime to apply to raise soil pH to a target — by soil texture, area and lime type (calcitic, dolomitic, hydrated, wood ash) — in kg per 100 m², lb per 1,000 ft² and total bags.

Exhaust fan capacity (CFM / m³ per hour) for a greenhouse or grow room from floor area, height, climate and light load — with air changes per minute, intake vent area and evaporative-cooling pad size.

Outdoor run area for a backyard flock — by breed size and access to free-ranging — with fence length, roosting bar, feeder, waterer and nest-box counts, and the coop floor area to match.

Volume of a garden or koi pond in litres and gallons for rectangular, circular, oval and irregular shapes with sloped sides — plus pump turnover, filter sizing, water-treatment dose and fill time.

How long to run a drip zone to deliver the water your plants need — from emitter flow rate, emitters per plant, plant water requirement or bed area and mm per week — with weekly schedule and zone flow check.

How many millimetres (or inches) per hour a sprinkler zone applies — from head flow rates and spacing, or from a catch-can test — and the run time to deliver a target depth without runoff.

Water flow from a garden hose by diameter, length and supply pressure — litres and gallons per minute, time to fill a pool, bucket or watering can, and how much a longer or thinner hose costs you.

How much anchor rode to pay out from water depth, bow height and tide — 5:1 to 10:1 scope for chain, rope or mixed rode — with holding-power notes, swing radius and the rode you should carry aboard.

Estimate a boat’s fuel burn from engine horsepower, engine type and throttle (or RPM) — litres and gallons per hour, nautical miles per litre, safe range and endurance with a reserve rule you choose, fuel and cost for a planned trip, and a burn table for every throttle setting. Already know your burn rate? Enter it directly.

Theoretical and actual boat speed from propeller pitch, engine rpm and gear ratio — prop slip percentage from a measured speed — and the pitch change needed to hit the engine’s rated rpm at wide-open throttle.

Horsepower needed for a boat from loaded weight, hull type and desired speed — planing threshold, recommended and maximum hp, pounds per horsepower and the transom capacity check.

When to start descending and at what rate — distance from the airport by the 3:1 rule, required feet per minute from ground speed, time to descend and descent gradient — for pilots and flight-sim users.

Fuel required for a flight — taxi, climb, cruise, alternate and reserve (VFR 30/45 min or IFR 45 min) — from trip distance, ground speed and burn rate, with endurance, fuel weight and the maximum payload left.

Takeoff weight and centre of gravity from empty weight and arm, pilot and passengers, baggage and fuel stations — moments, CG position, envelope check and how much weight you can still load.

Maximum operating depth for any nitrox blend at a 1.4 or 1.6 ppO₂ limit, the best mix for a planned depth, equivalent air depth, and the oxygen-exposure (CNS %) estimate for the dive.

Plan breathing gas for a dive from cylinder size, fill pressure, SAC rate, depth and time — gas needed, turn pressure by the rule of thirds, minimum “rock bottom” reserve for two divers ascending, and available bottom time.

How much drag to set on a spinning, baitcasting or offshore reel — 25–33% of line breaking strain, adjusted for leader, knots and rod angle — in kilograms and pounds, with a scale-check method and drag at full spool versus half spool.

Board feet in a saw log by the Doyle, Scribner and International ¼-inch log rules from small-end diameter and length — plus true cubic volume (Smalian) in cubic feet and metres and the sawmill overrun.

Measure tree height with a clinometer or phone inclinometer from distance and angles to the top and base (with slope correction), or by the shadow or stick method — with felling zone and the percent-scale shortcut.

Stem volume of a standing tree from diameter at breast height and height using a form factor — cubic metres and feet, basal area, board feet estimate, and plot basal area per hectare or acre from a tally of DBHs.

Exit pupil of a telescope–eyepiece combination from aperture, focal length and eyepiece focal length — magnification, lowest and highest useful powers, the eyepiece range for your scope and whether the image will look dim or wasted.

True field of view of an eyepiece in a telescope from apparent field, eyepiece and telescope focal lengths (or the field stop diameter) — degrees and arc-minutes, how many Moon-widths fit, star drift time and famous objects that fit the field.

Focal ratio, image scale in arc-seconds per pixel, sampling versus seeing (with 1×1 to 4×4 binning), camera field of view, relative exposure time and the effect of a Barlow or reducer — plus Dawes and Rayleigh limits, Airy disk size, the ideal planetary focal ratio, limiting magnitude, light grasp and eyepiece magnification, with presets for popular astro cameras.

Faintest star visible through a telescope from aperture and sky darkness (Bortle class or naked-eye limit), light grasp compared with the eye, gain from magnification, and the magnitude reach of common apertures.

Resolving power of a telescope from aperture: Dawes limit, Rayleigh criterion and the Airy disc size at a chosen wavelength, the magnification needed to see it, and which double stars and planetary details it can split.

How large the Moon, Sun or a planet will appear on your camera sensor at a given focal length — pixels and millimetres across, share of the frame, the focal length for a frame-filling Moon and a safe shutter speed to freeze its drift.

Electricity cost of a kiln firing from the kiln’s kilowatt rating, firing length, duty cycle and tariff — cost per firing, per piece and per shelf, monthly cost for a firing schedule, and bisque versus glaze firing comparison.

Scale a glaze or slip recipe from percentage parts to any batch weight — grams of each material and colourant, the water to add for a target specific gravity, checks that the base sums to 100, and cost of the batch from material prices.

How big to throw or build a piece so it ends up the right size after drying and firing — total shrinkage from a test tile or typical clay body values, wet size for a target fired size, fired size for a given wet size and the shrinkage factor for templates.

Plaster and water to mix for a mold from the volume to fill — consistency (water per 100 parts plaster) for pottery plaster, Hydrocal or plaster of Paris, weights of each, mix container size, working time and absorbency notes.

Turn a skincare or lotion formula written in percentages into grams for any batch size — every ingredient by phase, a check that it totals 100%, preservative and emulsifier ranges, batch cost and cost per jar.

How much oil to use for a soap mold: total batch weight from mold dimensions (loaf, slab or cavity), oil weight from the water and lye fractions, number and weight of bars, cure weight loss and the cost per bar.

Convert screenplay pages to screen time and back with the one-page-per-minute rule adjusted for dialogue- or action-heavy scripts, target page counts for features, TV episodes and shorts, act-break page targets, and word count in standard screenplay format.

Damage per second from base damage or a min–max range, flat and percentage bonuses, “more” multipliers, attack speed or RPM, crits, headshots or weak spots, multi-hit attacks, magazine and reload, damage over time and target mitigation — burst and sustained DPS, time to kill, a hit-outcome table and the best next stat upgrade.

Chance of getting at least one drop (or several copies) in N attempts from a per-kill drop rate or a “1 in X” rate: expected tries and their spread, tries and farming hours for 50%, 90%, 99% or your own confidence, the full drop-count distribution, dry-streak odds, a luck check for the runs you have already done, and the effect of drop-rate bonuses, extra loot rolls and shared party loot.

Turn armour or resistance into damage reduction with the common game formulas — armour ÷ (armour + K), hit-size armour (PoE-style), capped linear resistance or flat reduction — then effective HP from health, shields, extra reduction layers, dodge and block, penetration, healing and incoming DPS: hits to die, the biggest hit you survive, time to die and whether armour or HP is the better buy.

Hours to reach a target level from XP per kill, quest or run — with a polynomial or exponential XP curve, built-in RuneScape (OSRS), Minecraft, Pokémon and D&D 5e tables, your own pasted XP table or a known XP total. Shows XP still needed, kills or runs, sessions and calendar weeks at your play schedule, the finish date, a level-by-level schedule, and the effect of XP boosts, events, success rate, downtime and daily caps.

Theoretical top speed of an RC aeroplane or drone from propeller pitch and motor rpm (KV × voltage), real-world speed after slip, tip speed and Mach check, thrust-to-speed trade-off between pitch and diameter, and the prop that matches a target speed.

Thrust-to-weight ratio of a multirotor or RC aeroplane from motor thrust, motor count and all-up weight — hover throttle, spare thrust for climbing and wind, maximum payload for a target ratio, vertical acceleration and recommendations by flying style.

Convert between motor KV, pack voltage and rpm for brushless RC motors — no-load and loaded rpm by cell count, the KV to reach a target rpm on a given battery, the back-EMF/voltage limit, and how KV trades torque for speed when choosing props.

Size an electronic speed controller and battery for an RC aircraft or drone from motor max current, motor count and cell count — ESC rating with headroom, total current, watts, required C-rating and capacity for a flight time, wire gauge and connector recommendations.

Choose a screen printing mesh count for your ink and artwork: minimum mesh for a halftone LPI (4–5 × rule), mesh for fine lines, maximum mesh for the ink particles, the highest LPI your mesh holds, thread, opening, open area and theoretical ink volume from mesh data, wet deposit with the stencil, and ink needed for the run.

Convert bars and beats to minutes and seconds at any tempo and time signature, a duration into bars, or bars plus a duration into BPM. Plan a whole arrangement with start times for every section, turn a DAW position like 33.1.1 into a time, and get beat and note lengths (straight, dotted, triplet) in milliseconds, samples per beat and video frames.

Delay times in milliseconds for every note value at a given BPM (straight, dotted, triplet), reverb pre-delay and decay settings that sit on the grid, compressor attack and release starting points, and LFO rates in Hz for tempo-locked modulation.

Convert between cents, frequency ratios and semitones: the nearest note and cents offset for a measured frequency, the cents between two frequencies, a frequency shifted by cents, the frequency of any note at A = 440, 442, 432, 415 or a custom pitch, the closest simple ratio, and just vs equal-tempered intervals.

Work out the cost per round of hand-loaded ammunition from powder price and charge weight, primer, bullet and brass cost with brass reuse, compare with factory ammunition, and find the break-even round count that pays off a press and dies.

Calculate the diameter of the lit spot from beam angle and throw distance (and field angle at 10%), the beam angle needed to cover a given area from a given distance, centre illuminance from candela, and a table of spot sizes by distance for common beam angles.

Size an aquaponics system with the feed-rate ratio method: grow-bed area supported by a daily fish feed amount, fish tank volume and stocking, number of fish for a target harvest weight, plant count for the bed, and the media-bed volume, with the 1:1 to 1:2 tank-to-bed rules of thumb.

Convert electrical conductivity to ppm on the 500, 640 and 700 TDS scales and back, find how much concentrated nutrient to add to a reservoir to reach a target EC from the current reading, the top-up needed after evaporation, and crop-by-crop EC and pH targets.

Work out the daily light integral your plants receive from PPFD and photoperiod, the PPFD needed for a target DLI, the grow-light wattage for a canopy area from fixture efficacy (µmol/J), hours to run supplemental light in a greenhouse, and crop DLI targets from lettuce to tomatoes and cannabis.

Plan a mushroom grow: dry substrate and water to hydrate to the target moisture, bran or soy-hull supplement and gypsum, grain spawn by spawn rate or spawn-to-substrate ratio, number of grow bags or blocks, expected fresh yield from biological efficiency by species (oyster, king oyster, shiitake, lion's mane, wine cap, button), a flush-by-flush harvest calendar, and cost, revenue and cost per kilogram or pound.

How many seeds to sow for the plants you want: from target plant count, germination rate, seedling survival and a safety margin, the number of cells or trays, the sowing date counted back from the last frost, seeds per gram and packets needed, and the bed length the plants will fill at their spacing.

Calculate a greenhouse's heat loss from its surface area, glazing U-value (single glass, double poly, polycarbonate), wind exposure and the temperature difference between inside setpoint and the coldest night, size the heater in BTU/h and kW, and estimate seasonal fuel use and cost from heating degree days.

Calculate spoke length for building a bicycle wheel from the rim ERD, hub flange diameter, flange offset (centre to flange) and spoke hole diameter, for each side separately, with 1-, 2-, 3- or 4-cross or radial lacing and any spoke count — plus the recommended rounding and dish check.

Get the wheel circumference to program a bike computer from ETRTO / ISO tyre size (e.g. 25-622, 57-584) or common names (700×25c, 29×2.25, 26×1.95), with the rolled-out correction, the speed and distance error from a wrong setting, revolutions per km, and a table of common sizes.

Find the correct chain length for a derailleur or single-speed bicycle from chainstay length, largest chainring and largest cog using the rigorous equation and the big-big-plus-two method, in links and inches, with the quick-link / rivet count, the number of links to remove from a new chain, and 1x, full-suspension and Eagle 52 t notes.

Analyse a drivetrain: total gear range percentage for 1× and 2× setups, the ratio and percentage jump between each cog, gear inches and development per gear, duplicated gears on a double, cadence-speed spread, and a comparison of common cassettes (11-28, 11-34, 10-50, 10-52).

Estimate the tension balance between the two sides of a dished bicycle wheel from the flange offsets and spoke lengths, the target drive-side tension from rim rating and spoke type, the resulting non-drive tension, tensiometer readings in kgf and N, and whether an asymmetric rim or offset lacing would help.

Translate a bike fit into frame numbers: effective reach and stack at the handlebar from frame reach/stack, head-tube angle, spacers, stem length and angle; compare two frames or two stems, find the stem that reproduces your current position on a new frame, and check saddle setback and drop.

Estimate the filament weight, length and material cost of a 3D print from the model volume, surface area, wall and top/bottom thickness, infill percentage and material density (PLA, PETG, ABS, ASA, TPU, nylon) — and see how much each infill setting really saves.

Estimate FDM print time from the plastic volume, layer height, line width and print speed, with a realistic overhead for travel and acceleration, the volumetric flow the hot end must sustain, electricity cost, and a table showing how layer height trades quality for hours.

Work out the cost and print time of an MSLA / SLA resin print — resin used including supports and a failure allowance, wash IPA and electricity, price per litre — and the time from model height, layer thickness, exposure, lift/retract and bottom layers, with a per-part price when printing a full plate.

Calibrate dimensional accuracy for FDM and resin printing: get the slicer scale factor from a measured test print or from material shrinkage (ABS, ASA, nylon, PLA, PETG, resin), the design diameter needed for a hole to come out to size, and clearance for press, slip and free fits.

Plan a segmented bowl or vase ring — the miter angle for any number of segments, outside and inside segment lengths for a ring diameter and wall width, board length per ring with kerf, how a small angle error accumulates around the ring, and the stack of rings for a given height.

Calculate boat propeller slip from engine RPM, gear ratio, prop pitch and GPS speed — theoretical versus actual speed, slip percentage against the normal 8–20% range, and what changing pitch by an inch or two would do to WOT rpm and top speed.

Size a boat's bilge pump: recommended capacity by boat length and type, what a pump rated in GPH really delivers at your hose height and length, how fast water floods through a hull hole of a given size and depth, whether the pump can keep up, and battery run time.

Plan a backyard skating rink — gallons of water for the ice thickness and the yard's slope, hose fill time, liner size with overlap, board count and height for the low end, the weight of the ice, and how many cold nights the first freeze needs.

Grade a sewing pattern between sizes — enter the base size's bust, waist and hip and a grade per size (the standard 2 in / 5 cm or a custom rule) to get a full size table, then see how to split the grade across front, back and side seams and how much to add to lengths per size.

Work out how blurred the background will be: blur disc size on the sensor, as a percentage of the frame and in pixels, from focal length, aperture, subject distance or framing, background distance and sensor size. Includes depth of field on the subject, a blur-versus-distance chart and a same-framing lens comparison (50 mm f/1.4 vs 85 mm f/1.8 vs 135 mm f/2 vs a phone).

Match a camera to a telescope: pixel scale in arcseconds per pixel from pixel size and focal length (with reducer or Barlow), field of view in degrees and arcminutes, sampling verdict against your seeing (under-, well- or over-sampled), a binning suggestion, and whether the Moon, M31, M42 or the Pleiades fit the frame.

Work out which focal length frames a subject of a given size from a given distance on your sensor — or how far back to stand with the lens you have, or how wide a scene a lens covers at a distance — with horizontal, vertical and diagonal angles of view, the full-frame equivalent and a table of common focal lengths.

Find the aperture at which diffraction starts to soften your camera's images — the Airy disk diameter at each f-number compared with the pixel pitch from sensor size and megapixels — the diffraction-limited aperture, the effective resolution left at f/11, f/16 and f/22, and the best aperture for landscapes and macro.

Estimate the materials for a copper-foil or lead-came stained glass panel from its size and piece count — total seam length, copper foil rolls or lead came strips, solder weight, flux, glass area with cutting waste, zinc or lead border, and a time estimate — for suncatchers, windows and lampshade panels.

Work out how much macramé cord to cut — length per strand from the finished length and the project multiplier (4–8×, doubled for folded lark's-head cords), the number of cords, total metres, weight and cost by cord thickness — for wall hangings, plant hangers, keychains, bracelets and bags.

Plan a hand-bound book: folded sheets and evenly balanced signatures from the page count, spine width from paper caliper or gsm with sewing swell (and PPI), how many parent sheets to buy and which grain, thread length for kettle, Coptic or pamphlet stitch, and cut sizes for the cover boards, spine piece, mull, endpapers and cover cloth.

Choose origami paper: the square size that folds a crane, box, frog, lily, star or sonobe module to a wanted finished size (or the finished size from your paper), how many squares of each size cut from A4, Letter or A3 with the offcut, paper weight advice, and the sheet count and paper needed for modular kusudama and cubes.

Mix fibre-reactive tie-dye by the numbers — dye powder per colour for pale, medium or deep shades from the fabric weight, dye solution volume per garment, soda ash soak (1 cup per gallon) sized to your batch, urea, squeeze bottles, cure time and wash-out — for T-shirts, hoodies, socks and yardage.

Work out how many balloons a garland or arch needs — 5-inch, 11-inch and 16-inch counts per foot for classic, organic and double-stuffed styles, the strip or fishing-line length, inflation time with a pump, packs to buy, weight for hanging, and cost — for parties, weddings and backdrops.

Size a picture mat: window opening from the artwork with an overlap, border widths with a weighted bottom, the outer mat and frame size (or the borders that fit a standard frame you already have), double-mat reveals, and the glass and backing board to cut — in cm and inches.

Mix sugar syrup for honey bees by weight — 1:1 spring stimulative syrup, 2:1 autumn feed, thin 1:2 — from the litres you need or the sugar you have, with the syrup volume each mix yields, feedings per hive, how much stored "honey" each litre adds, fondant for winter emergency feeding and the cost per hive.

Check whether a honey bee colony has enough stores for winter — target kilograms by climate, what your capped frames hold (Langstroth deep/medium, National, Dadant, Warré), the shortfall converted to 2:1 syrup or fondant, a hefting weight target for the whole hive, and how long the stores last at typical winter consumption.

Turn an alcohol or sugar-roll mite count into an infestation percentage (mites per 100 bees), compare it with the seasonal treatment thresholds, estimate the total mites in the colony from the phoretic fraction when brood is present, and see the expected count after a treatment of a given efficacy and the mite growth if you wait.

Date every step of raising honey bee queens from a graft date, an egg-laying date or a walk-away split — cells capped, cell-protector and mating-nuc dates, emergence on day 16 from the egg, mating flights, first eggs, and the first brood check — plus drone timing and the window for a queenless split to raise its own.

Estimate daily and whole-lactation milk from dairy goats by breed — Nigerian Dwarf, Nubian, Alpine, Saanen, LaMancha, Oberhasli, Toggenburg — with a lactation curve from kidding date to dry-off, peak and persistency, how many does a household needs for its litres per day, milk-to-cheese yield, and the dry-off and re-kidding dates.

Convert raw (grease) fleece weight to clean scoured wool by breed type and yield percentage after skirting, value the clip by micron grade, and for hand-spinners see the yards of yarn a fleece will make at each weight and how many sweaters, hats or socks that is — for one sheep or a whole flock.

Size a Coturnix (Japanese) quail flock for eggs or meat: hens for your eggs per week (and the chicken-egg equivalent), males for fertile hatching eggs, floor or cage space, daily and yearly feed and cost, the 17-day hatch and 6–8 week lay/harvest timeline, dressed meat per bird, and replacement hatches to keep production steady.

Plan a backyard duck flock by breed — Khaki Campbell, Indian Runner, Welsh Harlequin, Pekin, Cayuga, Muscovy, Swedish and more: ducks needed for your eggs per week, feed per day and year with cost, drinking and bathing water and how often to change a pool, coop and run space, and the drake ratio for fertile eggs.

Build a sugar wash for a target volume and alcohol: kilograms of sugar, water, starting specific gravity and Brix, yeast and nutrient amounts, fermentation time by temperature, expected final ABV and litres of pure alcohol — plus the volume of 40% spirit it would make after distillation and the cost per litre.

Estimate what a distillation run will produce: litres of absolute alcohol in the wash, low wines from a stripping run, total spirit collected on a spirit run, the volumes to expect for foreshots, heads, hearts and tails by still type, the hearts diluted to bottling strength and the number of bottles — for pot stills, reflux columns and hybrid stills.

Estimate how much spirit a cask loses to evaporation over the years by barrel size and climate, how the ABV drifts up (dry, hot warehouses) or down (cool, damp ones), how many bottles remain at bottling strength, the equivalent aging time for small barrels with their high surface-to-volume ratio, and the value evaporated.

Target frequencies for tuning drums with a tuner app or Tune-Bot: fundamental and lug (tap) pitches for the batter and resonant heads of each tom, snare and kick by diameter and depth, the resonant-head offset for sustain or a fat, short note, the nearest musical notes, and interval schemes (fourths, thirds) to tune a whole kit so it sings together.

Size and season a humidor: how many cigars a box or cabinet really holds by ring gauge and length, the two-way humidity packs or beads needed to hold 65–72% RH, seasoning packs and time for a new Spanish-cedar humidor, how often to recharge, what temperature and humidity to run for aging versus smoking, and beetle-risk temperature limits.

Size the life-support for a koi or goldfish pond: pump flow for a full turnover every 1–2 hours with head loss, biological filter volume for the fish load, UV clarifier watts for clear water, aeration litres per minute, the maximum koi the pond supports, feeding-driven ammonia load, and monthly running cost.

Daily and monthly amounts for guinea pigs: unlimited hay by weight, measured pellets, a cup of vegetables with the vitamin C they must get from food, water, the minimum cage floor area for your herd (7.5 sq ft for two, more per extra pig), bedding volume for a C&C or fleece setup, weekly cleaning, and the monthly cost of keeping them.

Portion a house rabbit's food by body weight and age: hay volume (a body-sized pile a day), pellets in grams and cups (25 g per kg for adults, unlimited alfalfa for kits), leafy greens in cups, fruit and treat limits, water, monthly quantities and cost, the ideal-weight check, and the exercise space and litter needs for one or a bonded pair.

Check a hamster enclosure against modern minimums: unbroken floor area (≥ 5,000 cm² / 775 sq in for Syrians, 4,000 cm² for dwarfs; 100 × 50 cm recommended), bedding depth for burrowing (20–30 cm) converted to litres per fill and per month, the right wheel diameter and hide count, sand bath and food amounts, and the monthly cost — with common cages sized for comparison.

Set up and feed a bearded dragon by age: enclosure size from hatchling to adult (40 to 120+ gallons), basking spot and cool-side temperatures with the wattage to reach them, UVB tube strength, length and mounting distance, the insects per day and the greens-to-insects ratio that changes as they grow, calcium and vitamin dusting schedule, and monthly feeder costs.

Plan a leopard gecko setup: enclosure size by age, under-tank heat mat area and wattage with a thermostat for a 31–33 °C warm side, whether low-level UVB is worth adding, humid hide and moisture, the number and size of insects per feeding by age and weight, calcium and D3 schedule, healthy weight range, and monthly costs.

Check a tortoise’s weight with the Jackson ratio (weight ÷ shell length³) and its healthy weight band for Hermann’s, spur-thighed, Russian and marginated tortoises, judge fitness to hibernate with a weight-loss limit, and size the enclosure, daily food, heat, UVB and humidity for seven species.

Set up a betta tank properly: minimum and better tank sizes, heater wattage for a steady 25–27 °C in your room, a gentle filter flow that will not shred fins, water-change volume and frequency for the tank size and stocking, how long fishless cycling takes, tank-mate space rules, feeding pellets per day, and the running cost — with a sorority and divided-tank check.

Portion a pet bird's food by species and weight: daily pellets and seed in grams and teaspoons for budgies, cockatiels, lovebirds, conures and parrotlets, the pellet-to-seed ratio and how to convert a seed junkie, fresh vegetables and chop, egg food in moult and breeding, cuttlebone and grit rules, the healthy weight range and keel check, minimum cage and bar spacing, and monthly cost.

Measure a glaze or casting slip's specific gravity from a weighed 100 mL sample, use Brongniart's formula to find how much dry material and water it holds, and work out exactly how much water to add (or remove) to hit a target specific gravity for the whole bucket.

Convert an Orton pyrometric cone number to its end-point temperature at your kiln's final heating rate, compare cones, see how a slow ramp or a hold lowers the temperature needed, and pick the guide, target and guard cones for a witness pack.

Build a programmed kiln firing from up to four ramp-and-hold segments, see how long each takes, the total time to peak, when the kiln will be cool enough to unload, and the checks for a safe bisque or glaze schedule.

Estimate how many pots fit in your kiln: pieces per shelf from piece footprint and spacing, how many shelf levels the interior height allows with posts and shelf thickness, the posts you need, and the capacity of a full bisque or glaze load.

Work out how long to leave casting slip in a plaster mold for a target wall thickness using the square-root rule, how much slip to pour and how much stays in the piece, fired size after shrinkage, how many casts a mold can make per day before it saturates, and its working life.

Compare the thermal expansion (COE) of a glaze and a clay body to estimate the strain and stress that builds as the piece cools, judge whether the glaze will craze (tension) or shiver (compression), and see how far to move the glaze COE for a safe fit.

From a kiln's kilowatt rating and supply voltage get its full-load amps, the breaker size for a continuous load, the copper wire gauge (AWG and mm²) for the run length with voltage drop, whether it can use a plug or must be hard-wired, and what an hour of firing costs.

Estimate how much glaze a dipped or brushed piece takes from its surface area and coat thickness, the dry material that represents, how many pieces a bucket will glaze before it needs topping up, and the glaze cost per pot.

Estimate how many people a small boat can safely carry with the US Coast Guard length × beam ÷ 15 rule, the matching persons weight at 185 lb per adult, how gear, fuel and a motor eat into the total, and why the capacity plate and calm-water assumption matter.

Predict a planing powerboat's top speed from horsepower and loaded weight with Crouch's formula, pick the hull constant for your boat type, see the horsepower needed for a target speed, the pounds per horsepower, and how extra weight or a bigger motor changes the result.

Estimate a boat's underwater (wetted) surface area from waterline length, beam and draft for its hull type, then the litres or gallons of antifouling for the number of coats at the paint's coverage, the cans to buy, cost, and the extra for a boot stripe and touch-ups.

Size a boat's dock lines by length overall — diameter, bow, stern and spring line lengths and how many — plus fender diameter and number, cleat length to match the line, and the upgrades for storm mooring and exposed berths.

Find the anchoring load on your boat at 15, 30, 42 and 60 knots from the ABYC design-load table for its length and windage, then the proof-coil or high-test chain size, nylon rode or snubber diameter, shackle, chain weight per length, and the windlass pull you need.

Add up a boat's daily 12 V loads — fridge, lights, electronics, autopilot, pumps, inverter and charging — against the usable capacity of a lead-acid or lithium house bank to see how many days you can swing at anchor, what solar covers, and how many engine hours a day it takes to break even.

Size a boat's 12 V or 24 V DC wiring the ABYC way: minimum AWG (and mm²) for a 3% drop on critical circuits or 10% on non-critical ones over the round-trip length, checked against the 105 °C ampacity table with engine-room and bundling derates, plus the fuse or breaker to protect the wire.

Judge how stiff or tender a sailboat is: the Dellenbaugh angle from sail area, heeling arm, displacement and metacentric height, the ballast ratio, the righting moment per degree, the estimated heel angle at each wind speed and the wind at which to take the first reef.

Plan a coastal or offshore passage: effective distance with the upwind legs tacked out, realistic average speed against hull speed and current, hours and ETA from your departure time, whether you arrive in daylight, engine hours and fuel with reserve, and a watch rota for the crew.

Mix black-and-white film developer for your tank — concentrate and water for any dilution, the minimum concentrate per roll — and correct the development time from the 20 °C chart time for your actual temperature and for pushing or pulling, with the full process timeline.

Convert a known darkroom print exposure to a new print size using the magnification-squared rule, adjust for a different enlarging-lens aperture and a multigrade filter change, and see the result in seconds and f-stops with a table for standard paper sizes.

Plan a darkroom test strip in equal f-stop steps around a base exposure, get the cumulative and per-segment times for a progressive strip, and convert dodging and burning from stops to seconds so every print you make is repeatable.

Work out the exposure compensation for close-up and macro work from lens extension or magnification — the bellows factor, effective aperture, stops of light lost and the corrected shutter speed — for cameras without TTL metering, view cameras and extension tubes.

Track how many rolls or sheets a litre of working fixer and stop bath will process, how the fixing time grows as the fixer is used, when the clearing test says to discard it, and the wash sequence for archival negatives and prints.

Find the scanning resolution a negative or slide needs for a given print size at 300 ppi, the pixel dimensions and file size at 8 or 16 bits, the largest quality print your scanner's real resolution allows, and where film grain, not pixels, becomes the limit.

Apply the Zone System: place a metered shadow on the zone you want, see where the metered highlight falls, get the subject brightness range and the N+ or N− development the scene needs with adjusted development times and exposure settings from EV.

Add up what shooting film really costs — film, developing, scanning, prints and shipping — per roll, per frame and per keeper, your yearly spend at your shooting rate, and how many rolls it takes for a home developing and scanning setup to pay for itself.

Design a simple sweater from your gauge swatch: body stitches from chest measurement and ease, rows to the underarm and to the shoulder, sleeve cuff and upper-arm stitches with increase spacing, and the yards or metres of yarn and skeins to buy by size and yarn weight.

Get a custom sock recipe from your foot: cast-on stitches with the right negative ease for your gauge, cuff and leg rounds, heel-flap rows and gusset stitches, where to start the toe for your foot length, and how many grams and metres of sock yarn a pair takes.

Plan a crochet blanket from a standard size or your own dimensions: starting chain and rows from your gauge, the yarn each stitch type eats (single, half-double, double, granny, corner-to-corner), total yards and skeins with a border allowance, cost and hours.

Convert a cross-stitch chart's stitch count into the finished design size on 14, 16, 18 or 28-count fabric, the fabric to cut with a framing margin, how many skeins of floss it needs by coverage and strands, and how many hours it will take at your stitching speed.

Plan a weaving project: warp ends from width and sett, total warp length with take-up, shrinkage, fringe, sampling and loom waste, the yards or metres of warp and weft yarn, skeins to buy and the heddles per shaft — for rigid heddle and floor looms.

Identify a handspun or mystery yarn's weight category from wraps per inch, work out its grist in yards per pound and metres per 100 g from a weighed sample, the plied twist angle and TPI for a balanced yarn, and how much fibre to spin for a project.

Scale a natural dye recipe to your fibre: alum, cream of tartar or tannin mordant amounts from the weight of fibre for wool, silk or cotton, the dyestuff needed for a light, medium or deep shade, bath volume at the right liquor ratio, and iron or copper modifier amounts.

Size a knitted or crocheted piece before felting (fulling) so it shrinks to the finished dimensions you want — from a felted swatch or typical shrinkage rates by fibre — plus wet-felting layout size for flat felt and the extra fibre for a 3D resist project.

Add up an RV's 12 V loads off-grid — furnace blower, 12 V fridge or propane fridge control board, water pump, lights, fans, inverter loads and device charging — against usable battery capacity to see how many days you can boondock, what your solar covers, and the generator hours per day to break even.

Estimate how long an RV's propane lasts from the furnace duty cycle at your outdoor temperature, the absorption fridge, water heater cycles and cooking — gallons and pounds per day, days per 20 or 30 lb cylinder or onboard tank, and refill cost.

How many showers an RV water heater gives before it runs cold: hot-water fraction from tank, shower and cold-water temperatures, shower minutes per tank at your shower head's flow, recovery time on propane, electric or both, and how a tankless heater compares.

Check whether your truck-and-trailer or motorhome-and-toad combination fits a campsite: total hitched length vs the listed site length, whether you can leave the tow vehicle attached, back-in swing clearance for a trailer, road width needed to turn, and low-clearance limits for the route.

Plan a year of hay for your horses: pounds per day from body weight and the share of the diet that is hay, days off pasture, total tons and bales (small squares, large squares or rounds) with waste, the barn floor area and stack height needed, and the cost with a comparison of bale types by price per ton.

Work out how many acres your horses need from forage yield, grazing season, utilisation and how much of the diet pasture supplies, or how long a given pasture will carry them; plan rotational paddocks with rest periods and see how much hay makes up the shortfall.

Estimate how much bedding your horse stalls use per week and per year by bedding type and stall hours, the manure and soiled bedding they produce in cubic yards, the compost pile or dumpster capacity that needs, and what buying bedding and hauling manure costs.

Estimate how much water your horses drink per day from body weight, temperature, work and diet, size a trough or automatic waterer so it holds a day or two, see how long a hose takes to fill it, the freeze-protection heater wattage and its running cost, and the signs of dehydration to watch.

Decide whether and how heavily to blanket a horse tonight from the temperature, wind chill and rain, its coat and clipping, shelter, body condition and age, with the fill weight in grams, when to change or remove it, and the signs of an over- or under-blanketed horse.

Calculate a horse's daily digestible-energy requirement from body weight, workload, growth, pregnancy or lactation using NRC guidelines, then build a ration: how much of your hay meets it, whether grain or a fat supplement is needed, forage minimum checks, and how a calorie surplus or deficit changes weight.

Plan a square foot garden: how many squares your raised bed has, how many plants of each vegetable go in a square (1, 4, 9 or 16) and how many seeds or seedlings to buy — metric or feet.

How many tulip, daffodil, crocus, allium or dahlia bulbs do you need? Enter the bed size to get the number of bulbs, planting depth, spacing and the season to plant — metric or US.

How many hedge plants do you need? Enter the hedge length and plant type — privet, boxwood, yew, laurel, arborvitae, Leyland cypress — for a single or double staggered row, with spacing and cost.

When will your vegetables be ready? Enter the planting date and crop to get the first harvest date and harvest window from days to maturity — tomatoes, peppers, lettuce, carrots, garlic and more.

Estimate how much lead weight to start with for scuba diving from your body weight, wetsuit or drysuit, salt or fresh water and aluminum or steel tank — then fine-tune with a buoyancy check.

Spread increases or decreases evenly across a row or round in knitting or crochet: how many stitches to work between each one, how many times to repeat, and your new stitch count.

Convert knitting needle sizes between metric millimetres, US numbers and old UK/Canadian sizes, and crochet hooks between mm and US letters — with the yarn weight each size suits.

Plan a knitted beanie from head circumference and gauge: stitches to cast on with negative ease, rounds to knit before the crown and the crown decreases, rounded to fit your rib and sections.

Work out the finished size of a quilt from block size, blocks across and down, sashing and borders — with the closest standard bed size, block count, sashing pieces and binding length.

Find the right tablecloth size for a rectangular, square, oval or round table from the drop you want, plus the cut size with hems and how much fabric to buy for a sewn tablecloth.

Work out how much thread to cut for hand saddle stitching leather from seam length, stitch spacing (pricking iron pitch) and leather thickness, with the number of stitches and the thread-to-seam ratio.

Keep the same exposure when you change aperture, shutter speed or ISO: enter your metered settings, change two of them and get the third, with the nearest standard setting and the stops each change adds.

Find the slowest shutter speed that freezes a moving subject from its speed, distance, focal length, sensor size and resolution, or see how many pixels of motion blur a shutter speed gives.

Find the slowest shutter speed you can hand-hold without camera shake using the reciprocal rule, adjusted for crop factor, image stabilization stops and high-resolution sensors.

Get the right camera settings to photograph the Moon with the Looney 11 rule: shutter speed for your ISO and aperture, adjusted for the Moon phase and haze, with the nearest standard speed.

Plan a star trail photo: number of frames, length of the trail arc from Earth's rotation (15° per hour), trail length on the sensor and the memory card space for a stacked sequence.

See how slow your footage plays: recording frame rate vs. timeline frame rate gives the slow-motion factor, playback speed, clip length on the timeline, frames recorded and the 180° shutter speed.

Work out any polyrhythm such as 3 against 2, 4:3 or 5:4: note spacing in milliseconds for each rhythm at your tempo, the common grid (LCM) and a pulse-by-pulse chart of where the notes fall.

Find a safe wood lathe speed for a bowl or spindle blank from its diameter with the 6,000–9,000 rule: starting RPM for rough or unbalanced blanks, top speed for balanced work and rim speed.

Calculate the bandsaw blade length you need from the wheel diameters and the distance between wheel centres, for equal or unequal wheels, in millimetres, inches and feet-and-inches.

Find the moisture content wood will settle at for a given temperature and relative humidity (USDA Wood Handbook formula), and whether your boards will shrink or swell compared with a meter reading.

Work out how much paint mix an acrylic pour needs for your canvas size, sides included, then split it into pouring medium and paint by ratio and into cups per colour.

Size a vermicomposting worm bin from the food scraps you make each week: bin floor area and dimensions, pounds or kilos of red wigglers to start, worm count and bedding volume.

How high to hang a hammock: hang point height and strap length from the distance between trees or posts, hammock length, sit height and hang angle, plus the tension on each strap.