Science Calculators

Calculate the kinetic energy of a moving object from its mass and velocity.

Find final velocity, displacement and average velocity from initial velocity, acceleration and time.

Calculate force from mass and acceleration using F = m·a, plus the object's weight under gravity.

Calculate gravitational potential energy from mass, height and gravity using PE = m·g·h.

Calculate mechanical work from force and distance, and the power from the time taken.

Solve for voltage, current, resistance or power from any two known values — all 12 Ohm's law wheel formulas, unit choices from µA to kV and MΩ, worked steps and a resistor wattage check.

Find the equivalent resistance of up to four resistors wired in series or in parallel.

Calculate the charge stored on a capacitor and its stored energy from capacitance and voltage.

Solve ρ = m ÷ V for density, mass or volume with unit menus (g, kg, lb, mL, L, m³, ft³, g/cm³, lb/ft³ and more), a table of common material densities, specific gravity, sink-or-float and the worked steps.

Calculate the escape velocity from a planet or moon given its mass and radius.

Calculate the Reynolds number of a flow and classify it as laminar, transitional or turbulent.

Calculate the restoring force and stored energy of a spring from its stiffness and displacement.

Calculate pH, pOH and hydroxide concentration from the hydrogen-ion concentration of a solution.

Solve the ideal gas law PV = nRT for pressure, volume, moles or temperature using R = 0.082057 L·atm/mol·K.

Use Boyle's law to find the new volume of a gas when its pressure changes at constant temperature.

Use Charles's law to find the new volume of a gas when its temperature changes at constant pressure.

Find molarity from moles or grams, the mass of solute to weigh for a target concentration, or the volume to make — with unit menus (mol/mmol, g/mg, L/mL/µL, M/mM/µM/nM), common lab compounds, mass concentration, normality, a dilution table and the steps.

Solve the half-life equation for any unknown — amount remaining, initial amount, half-life or elapsed time — with time-unit dropdowns, isotope presets such as carbon-14, the decay constant and mean lifetime, a decay curve and the worked steps.

Calculate the heat energy needed to change a substance’s temperature from its mass, specific heat and temperature change.

Calculate how much a material lengthens with temperature using its linear expansion coefficient.

Convert between the wavelength and frequency of light and find the photon energy in joules and electronvolts.

Use Snell's law to find the angle of refraction when light passes between two media, and detect total internal reflection.

Calculate molality (moles of solute per kilogram of solvent), the temperature-independent measure of concentration.

Estimate the CO₂ your car emits each year from your annual mileage and fuel economy, using the EPA gasoline emission factor.

Estimate the CO₂ from your air travel per passenger, from flight distance, trips per year and cabin class.

Convert your household electricity use into CO₂ emissions using your grid’s carbon intensity.

Find how many trees it takes to offset a given amount of CO₂, based on the carbon a growing tree absorbs each year.

Estimate the hidden water behind your diet — the litres it takes to produce your food each day and year.

See the plastic bottles, money and CO₂ you save each year by switching to a refillable water bottle.

Estimate the CO₂ you save each year by recycling instead of sending material to landfill.

Estimate how much rainwater your roof can collect from its area, local rainfall and collection efficiency.

Estimate the annual CO₂ your solar array offsets by displacing grid electricity.

Estimate the money and CO₂ you could save each year by cutting home energy waste after an audit.

Compare the lifetime driving CO₂ of an electric car against a gasoline car over the same miles.

Estimate the transport CO₂ behind your food from its weight, distance travelled and mode of transport.

Convert a target seeding population into pounds of seed per acre, adjusted for germination and purity so you plant the bulk rate you actually need.

Estimate final plants per acre from row width, in-row seed spacing and emergence — the stand your planter settings actually deliver.

Estimate corn grain yield in bushels per acre before harvest using the yield-component method — ear count, kernels per ear and kernel weight.

Work out how many head a pasture can carry from forage yield, utilization and grazing days — plus acres per animal unit.

Size a daily feed ration from body weight and dry-matter intake, split it into forage and concentrate, and estimate the feed cost.

Plan winter hay: how many bales you need from head count, daily intake, feeding days, waste and bale weight — plus total tonnage and cost.

Estimate the tons of silage in a bunker or pile from its length, width, average depth and packed density.

Bushels a round or rectangular grain bin holds from its diameter (or length and width) and grain depth, with a peaked top from a measured height or the angle of repose, a hopper (cone) bottom, compaction, weight in tons for corn, soybeans, wheat and other crops, how full the bin is, and a depth-by-depth capacity table.

Turn a target N-P-K rate per acre into pounds of blended fertilizer product, and see which nutrient is the limiting one.

Mix a sprayer correctly: total product and water for your acres, plus how much product goes in each tank at your spray volume.

Convert an irrigation depth over an area into gallons and acre-feet, and find how long your pump must run at a given flow rate.

Convert a field’s length and width in feet into acres, square feet, hectares and square meters for planning and mapping.

Convert indicated airspeed to true airspeed using pressure altitude — the thinner the air, the faster you are really flying.

Find the density altitude from pressure altitude and temperature — the altitude your aircraft, wings and engine actually feel.

Break the reported wind into crosswind and headwind components for your runway — the numbers that decide if you can land.

Turn usable fuel and fuel flow into endurance and still-air range — with a reserve check before you launch.

Add up empty aircraft, occupants and fuel to find gross weight and centre of gravity — the moment arithmetic behind every loading sheet.

How far can you glide from a given height? Turn your glide ratio (or best-glide speed and sink rate) and height above the ground into the distance you can reach, with headwind or tailwind, time aloft, glide angle, a pattern-altitude reserve and a reach table by altitude.

Convert an altitude change and the time it took into a rate of climb in feet per minute, and the glide/climb gradient.

Compute the shortest distance between two latitude/longitude points on Earth with the haversine formula — in nm, km and miles.

Find the heading to hold and the groundspeed you will make when a wind pushes you off your desired course.

Convert knots to miles per hour, km/h, m/s, ft/min and ft/s, or any of those back to knots, with the Mach number, Beaufort wind force, hurricane category, distance per hour and day, travel time and a conversion table.

Convert nautical miles to statute miles and kilometres — and see why a sea mile is longer than a land mile.

Estimate a displacement boat’s hull speed from its waterline length — the natural speed limit set by its own bow wave.

Convert an earthquake magnitude into the seismic energy it releases (joules, TNT, Hiroshima bombs, electricity), its seismic moment and size class, compare two magnitudes by energy and shaking amplitude, or turn an energy back into a magnitude, with the Gutenberg–Richter or USGS energy relation.

Estimate how far away an earthquake struck from the delay between the fast P-wave and the slower S-wave at your location.

Find the "feels like" temperature from air temperature and wind speed using the official North American wind chill formula.

Calculate the "feels like" temperature in hot, humid weather from air temperature and relative humidity using the NWS heat index.

Find the dew point — the temperature at which air becomes saturated and dew, fog or condensation forms — from temperature and humidity.

Compute relative humidity from the air temperature and the dew point using saturation vapour pressure — the physical definition of humidity.

Work out how much water falls on a roof or plot from the rainfall depth and area in litres, gallons and cubic metres, and how much you can harvest after surface and first-flush losses, with tank fill, days of supply and the roof area needed for a target.

Convert a depth of snow into the amount of liquid water it holds, from the snow depth and its density or snow-to-water ratio.

Convert between rise, run, slope percentage grade, angle in degrees, 1 : N ratio and roof pitch — start from any one with a length to get the missing rise, run and slope length — in metres, feet, inches or other units, compared with ramp, road, rail, roof and stair limits.

Estimate the flow rate of a river or channel from its width, mean depth and current speed — the volume of water passing each second.

Estimate the water level at any time between high and low tide using a simple harmonic (cosine) model of the tidal cycle.

Turn the delay between a lightning flash and its thunder into the distance to the strike — the classic "flash-to-bang" count.

Find the great-circle distance between two latitude/longitude coordinates using the haversine formula.

Calculate the initial compass bearing (forward azimuth) of the great-circle route between two coordinates.

Find the geographic midpoint (halfway point) along the great-circle path between two latitude/longitude coordinates.

Find the destination coordinates given a start point, an initial bearing and a distance travelled.

Convert coordinates in degrees, minutes and seconds (DMS) to decimal degrees, and see the decimal-to-DMS breakdown.

Find the UTM grid zone number, hemisphere band and central meridian for any longitude and latitude.

Estimate the nominal UTC offset and local solar time for any longitude, based on 15° of longitude per hour.

Estimate the Sun’s altitude above the horizon for a given latitude, day of year and solar time.

Convert a measured distance on a map to real-world ground distance using the map’s scale ratio.

Calculate the surface area of a latitude/longitude bounding box on the Earth’s sphere.

Find the grade (percent slope), angle, ratio and slope length of a road, trail or route from rise and run, start and end elevations, distance along the path or a whole elevation profile — with total ascent and descent, steepest section, a profile chart, climb difficulty and optional walking time.

Convert a compass bearing in degrees to its cardinal direction (N, NE, E…) on the 8- and 16-point compass.

Convert between apparent magnitude, absolute magnitude and distance — solve for any one, or for the extinction — with distance in parsecs, light-years, kpc, Mpc or from a parallax, dust extinction from A or E(B−V), luminosity relative to the Sun, the distance uncertainty from a magnitude error and how bright the object would look at other distances.

Inner and outer edges of a star’s habitable zone with the Kopparapu et al. climate limits from luminosity and temperature, radius and temperature, or mass; where a planet at a given distance sits, the stellar flux it receives, its equilibrium temperature, orbital period and a table of every limit.

Angular diameter from physical size and distance (or size from angle), in degrees, arcminutes and arcseconds — with comparisons to the Moon, a fist at arm’s length and telescope resolution.

Moment magnitude Mw from fault area, slip and rigidity (or seismic moment), the energy released in joules and TNT tons, and how two earthquakes compare in energy.

Tsunami speed from ocean depth (c = √(g·h)), travel time over a distance or a multi-segment path of changing depth, wavelength from the period, a dispersion check, and how the wave slows and grows near the coast (Green’s law with funnelling).

Find the Saffir–Simpson hurricane category from maximum sustained wind in mph, km/h, knots or m/s, using NHC’s official ranges. Converts 10-minute (WMO) winds to the 1-minute standard, estimates peak gusts, shows the wind needed for the next category, the expected damage, the historical pressure band and the full scale table.

Convert wind speed to Beaufort force (0–12) and back — description, effects on land and sea, wave heights, and the speed in knots, mph, km/h and m/s.

Density of moist air from temperature, pressure and relative humidity (or dew point) — with the dry-air value, water-vapour partial pressure, specific volume and altitude correction.

Air pressure at any altitude from −1,000 m to 86 km (U.S. Standard Atmosphere 1976 / ISA), or the altitude from a pressure reading, in hPa, kPa, inHg, mmHg, psi or atm, with temperature, air density, speed of sound, equivalent oxygen, inspired oxygen pressure and the boiling point of water. Set a non-standard sea-level pressure or a hot/cold day offset.

Minutes to sunburn from the UV index and your skin type, with and without sunscreen — SPF-adjusted safe time, the recommended protection and the reapplication interval.

How much carbon dioxide a tree (or a planting) absorbs per year and over its life from trunk diameter or age and species type — with the biomass method, tonnes offset and equivalent car miles.

Convert methane, nitrous oxide and F-gas emissions to CO₂-equivalent with IPCC AR6 global warming potentials over 100 or 20 years — totals, shares and the gas that dominates.

Age of a rock, mineral or sample from the daughter/parent ratio or the fraction of parent left, for U-238, U-235, Th-232, K-40, Rb-87, Sm-147, Lu-176, Re-187, C-14 or a custom half-life. Also works backwards from a known age, with uncertainty, a decay table and chart.

Power in the wind per square metre and what a turbine of a given rotor diameter can extract — Betz limit, real efficiency, air-density and hub-height corrections, and annual energy.

Sunrise, sunset, solar noon, day length and civil, nautical and astronomical twilight for 46 preset cities or any latitude and longitude, with golden and blue hours, sun directions and a full monthly table — using the NOAA solar equations.

Pressure altitude from field elevation and the altimeter setting (inHg or hPa) with the FAA rule (29.92 − setting) × 1,000 + elevation, the exact standard-atmosphere value, or from station pressure (NWS formula), plus ISA temperature and density altitude.

Bank angle for a standard-rate (3°/s) turn at any true airspeed, turn radius and diameter, time for a 180° or 360° turn, load factor and stall-speed increase at that bank.

Hydraulic retention (detention) time of a tank, clarifier, lagoon, pond or contact pipe from its size or volume and the flow, in any unit (m³, gallons, MGD, gpm, L/s) — with surface overflow rate, weir loading and horizontal velocity for clarifiers, peak-flow and parallel-unit checks, chlorine CT with EPA baffling factors, and the flow that gives a target detention time.

How much chlorine to dose a tank, cistern, well or pipeline to a target mg/L (ppm): household bleach by its sodium hypochlorite %, pool liquid chlorine, calcium hypochlorite, dichlor, trichlor or chlorine gas. Works out well and pipe volumes, adds the water’s chlorine demand, and gives household measures, a dose table, CT and the dechlorination chemical needed afterwards.

Brightness ratio between two magnitudes (Pogson scale), combined magnitude of a double star, absolute magnitude and luminosity from apparent magnitude and distance, and distance from the distance modulus.

Psychrometric properties from air temperature (°C, °F or K) and relative humidity, dew point, wet-bulb temperature or absolute humidity: saturation and actual vapour pressure, vapour pressure deficit, absolute humidity, mixing ratio, specific humidity, enthalpy, air density, heat index and the water to add or remove in a room — with a choice of Magnus, Arden Buck, Tetens or Wagner–Pruss formulas.

Paste per-paper citation counts to get a researcher’s h-index, i10-index, g-index, e-index, total and median citations, h-core share and Hirsch’s m-quotient, plus the citations needed to reach the next h or a target h, a ranked table and a Hirsch plot.

Calculate a journal’s two-year Journal Impact Factor (JIF) the way Clarivate’s JCR does, plus the five-year JIF, JIF without self-citations, immediacy index, Scopus CiteScore (four-year window) and, from the category rank, the JCR quartile and JIF percentile.

Darcy's law calculator: groundwater discharge Q = K·i·A from hydraulic conductivity, hydraulic gradient and flow area; Darcy flux, average linear (seepage) velocity using effective porosity, and travel time for a plume or tracer over a set distance.

Predict drawdown around a pumping well with the full Theis solution and the Cooper–Jacob approximation from pumping rate, transmissivity, storativity, distance and time, with unit choices, the unconfined-aquifer correction, well efficiency, interference with a neighbouring well, radius of influence, specific capacity and drawdown-versus-distance and drawdown-versus-time tables and charts.

Analyse a constant-rate pumping test: transmissivity from the drawdown change per log cycle of time, storativity from the zero-drawdown intercept, hydraulic conductivity from aquifer thickness, plus a Thiem steady-state check from two observation wells.

Calculate porosity from bulk and particle density (or enter it), specific retention and void ratio, the water stored in an aquifer and the part that drains by gravity, recharge against pumping, the yearly water-table or head decline for unconfined and confined aquifers, how long storage lasts and the sustainable pumping rate, with unit choices for area, thickness, flow and recharge.

Work out the vertical speed needed to lose a given altitude over a given distance at your ground speed, the resulting descent angle, the distance and time to descend, and the 3-degree glidepath rate (ground speed × 5) with a table of rates by ground speed.

Find the speed at which a tyre starts to hydroplane from its inflation pressure with NASA’s 9√P rule (knots) for a rotating tyre and 7.7√P for a non-rotating tyre at touchdown, in knots, mph and km/h, with your speed margin, the risk at your water depth and a table by tyre pressure.

Estimate how much longer the takeoff roll and how much weaker the climb rate become at high, hot airports: density altitude from pressure altitude and temperature, Koch-chart style percentage increase in takeoff distance and decrease in rate of climb, and adjusted figures from your sea-level book values.

Estimate the height of the cumulus cloud base from the surface temperature and dew point using the dry adiabatic lapse rate spread rule (≈ 400 ft or 125 m per °C), the freezing level, convective condensation height and how the spread changes through the day.

Flight-planning calculator for the equal time point (critical point) and point of safe return: distance and time from departure using true airspeed and wind components out and back, with the endurance available and the effect of a headwind or tailwind on both points.

Calculate turn radius and rate of turn from true airspeed and bank angle, the load factor and stall-speed increase in the turn, the bank needed for a standard-rate turn, the 180° reversal time and the radius needed for a canyon or valley turn.

Fire hose friction loss with FL = C × Q² × L for ¾ to 6 inch hose (or your own flow-tested coefficient, US or metric): loss per 100 ft and for the whole lay, parallel (siamese) lines, the most flow or length within a target loss, an optional pump discharge pressure, and a comparison across hose sizes.

Calculate fire engine pump discharge pressure: nozzle pressure plus hose friction loss, appliance loss and elevation gain or loss for attack lines, standpipes and master streams, with nozzle flow from nozzle type and a breakdown of each term.

Estimate the water flow required to control a structure fire with the National Fire Academy quick-calculation formula (length × width ÷ 3 × floors × percent involved) and the ISO needed-fire-flow method by construction class and occupancy, plus exposure charges, handlines needed and water-supply duration.

Enter the centimorgans shared with a DNA match to see the percentage of DNA shared, the most likely relationships and which are ruled out, using published shared-cM ranges, plus the segment count and largest-segment sanity check and what to compare next.

Calculate illuminance in lux or foot-candles at any distance from a point source using the inverse square law and Lambert's cosine law: from candela or from lumens and beam angle, on a tilted surface, the distance for a target level, and a distance table.

Blend two light sources of different correlated colour temperatures to find the resulting CCT from mixing ratios (mired-weighted), the ratio needed to hit a target CCT, the mired shift of gels and filters, and how tunable-white fixtures map warm and cool channels across the day.

Use Hubble's law v = H₀ d to convert a galaxy's recession velocity or redshift into its distance in megaparsecs and light-years (or the reverse), with the light-travel look-back time, the Hubble time and a note on where the linear law stops working.

Estimate the number of communicating civilisations in the Milky Way with the Drake equation — star formation rate, fraction with planets, habitable planets per system, fractions developing life, intelligence and technology, and civilisation lifetime — with pessimistic and optimistic presets.

Calculate the Hill sphere radius of a planet, moon or exoplanet from its orbit and the two masses, with eccentricity, the stable limits for prograde and retrograde moons (Domingos et al. 2006), a check of any satellite distance, presets for solar-system bodies and a reference table.

Calculate the synodic period between two orbiting bodies from their sidereal periods — how often Mars reaches opposition, Venus its inferior conjunction, or two moons line up — plus the next alignment date and a table for every planet relative to Earth.

Calculate the tidal acceleration a body exerts across another — the Moon and Sun on Earth, a planet on its moon, a black hole on an astronaut — from mass, distance and the size of the affected body, with the stretching force in g, the tidal bulge estimate and a comparison table.

Find the habitable zone of a star from its luminosity and temperature, radius or mass, using the Kopparapu et al. climate limits: conservative and optimistic edges in AU, the stellar flux at each edge, orbital periods, planet-mass effects, and whether a planet at a given distance and eccentricity is inside, with its equilibrium temperature.

Calculate how much a transiting exoplanet dims its star — transit depth from the planet-to-star radius ratio in percent and parts per million — plus the transit duration from period and orbital distance, the planet radius implied by a measured depth, and detectability against photometric noise.

Size an MPPT or PWM solar charge controller: minimum output current with the 1.25 safety factor, the next standard amp rating, and the PV input voltage rating from the cold-temperature open-circuit voltage.

Convert radiation dose between gray, sievert, rad and rem (and mGy, mSv, µSv, mrem), switching between absorbed and equivalent dose with the ICRP 103 radiation weighting factor for each radiation type.

Find the best tilt angle for solar panels at your latitude — fixed year-round, adjusted twice a year or four times a year — plus which way to face and the noon sun height month by month.

Cooling tower range, approach and efficiency, evaporation, drift and blowdown losses, make-up water from cycles of concentration, and heat rejected in kW and tons of refrigeration.

Calculate the Canadian humidex from air temperature and relative humidity or dew point — the Environment Canada formula, the comfort level from little discomfort to dangerous, and the vapour pressure.

Work out the apparent ("feels like") temperature from air temperature, humidity and wind with the Steadman formula used by the Australian Bureau of Meteorology — in the shade or in the sun.

Find the wet-bulb temperature from air temperature and relative humidity with Stull’s formula — plus the wet-bulb depression, the dew point and the heat-stress level for the human body.

Estimate the air temperature at a mountain summit or any altitude from the temperature at a lower point, using the standard, dry or moist adiabatic lapse rate — with the freezing level and a table by height.

Convert a barometer reading at your elevation (station pressure) to sea-level pressure, or sea-level pressure back to station pressure, from altitude and temperature — in hPa, inHg, mmHg and kPa.

Estimate daily reference evapotranspiration (ET₀) from maximum and minimum temperature, latitude and date with the FAO-56 Hargreaves equation — plus crop water use with a crop coefficient and litres for your area.

Calculate growing degree days (GDD, heat units) from daily maximum and minimum temperatures and a base temperature — simple average or the corn 86/50 method — and the days left to reach a crop or insect GDD target.

Find the chance of a 100-year flood, earthquake or storm happening at least once in a given number of years — or the return period to design for an acceptable risk — with the binomial exceedance formula.

Convert a PM2.5, PM10, ozone, carbon monoxide or nitrogen dioxide concentration into the US EPA Air Quality Index (2024 breakpoints) — with the AQI category, color band and health advice.

Convert light-years to parsecs, astronomical units, kilometres and miles — and back — with the IAU definitions, plus how long light takes to cover the distance.

How long does it take to get to Mars, Venus or Jupiter? Compute the Hohmann transfer time, heliocentric delta-v, launch phase angle and launch-window interval between any two planets.

Estimate the energy of an asteroid or meteorite impact in megatons of TNT and Hiroshima bombs, and the size of the crater it would leave, from its diameter, density, speed and entry angle.

Calculate a planet’s or exoplanet’s equilibrium (blackbody) temperature from its star’s luminosity, orbital distance and Bond albedo — in kelvin, °C and °F — plus the stellar flux it receives.

Estimate how old a tree is without cutting it, from the trunk circumference or diameter at breast height and the species growth factor (oak, maple, pine, birch and more) — the ISA arborist method.

How far is the horizon, and how much of a distant ship, island or building is hidden by the curve of the Earth? Enter your eye height and the distance — with or without atmospheric refraction.

Estimate clear-sky solar irradiance in W/m² on a horizontal surface and on a tilted solar panel for any latitude, date and time — with sun elevation, air mass, angle of incidence and panel output.

Find the wavelength, speed, group speed and power of ocean waves from the wave period and water depth with the linear dispersion relation — deep, intermediate or shallow water — for surf and swell forecasts.

Estimate a cow, steer or heifer’s live weight without a scale from heart girth and body length with the Schaeffer formula — in kg or lb, with a likely range and a weight-by-girth table.

Estimate a pig or hog’s live weight without a scale from heart girth and body length (girth² × length ÷ 400) in kg or lb, plus the likely carcass weight and a weight-by-girth table.

Calculate average daily gain (ADG) of cattle, pigs, sheep or goats from two weighings — total gain, gain per month, percentage gain and the days left to reach a target weight.

Convert a cow’s somatic cell count (SCC) into the DHI linear score (SCS), read the udder-health status and estimate the milk lost per lactation to subclinical mastitis.

Convert a cow’s daily milk, fat % and protein % into energy-corrected milk (ECM) and 4% or 3.5% fat-corrected milk (FCM), and get feed efficiency (ECM ÷ dry matter intake).

Estimate pasture forage dry matter per hectare or acre from clipped quadrat samples, the usable forage in a paddock and how many days it will feed your herd.

Calculate how much nitrogen to apply per hectare with the N balance method — crop demand from target yield minus soil nitrate and mineralisation, divided by fertilizer efficiency — and the kg of urea or other product.

Calibrate a knapsack or backpack sprayer: spray a measured test area with water, get your application volume in L/ha, the area each tank covers and how much pesticide or herbicide to put in every tank.

Calculate how much water a center pivot applies per revolution (mm or inches), its irrigated area, system capacity per day, flow per hectare and end-tower speed from radius, flow and revolution time.

Work out how much to feed tilapia each day from the number of fish, average weight and survival, using the FAO feeding table — biomass, feeding rate, meals per day and feed to reach harvest weight.

Estimate soybean yield before harvest from plants per m², pods per plant, seeds per pod and 1,000-seed weight — in t/ha, kg/ha and bushels per acre, with a seed-size sensitivity table.

Work out how many litres of fluid a scouring, dehydrated calf needs in 24 hours: dehydration deficit plus maintenance and ongoing diarrhoea losses, with hourly rates and the oral-or-IV decision.

Calculate how much colostrum a newborn calf needs at the first and second feeding from its birth weight, and check colostrum quality from a Brix refractometer reading.

Calculate the temperature-humidity index (THI) from air temperature and relative humidity and see the cattle heat-stress level — from the 68 stress threshold for dairy cows to severe — with cooling advice.

Predict when a cow, heifer, sow, ewe, goat or mare will come back into heat from her last heat date — next heat, watch window, upcoming cycles, breeding tips and the due date if she was bred.

Standardise a beef calf’s weaning weight to 205 days of age with the BIF formula and age-of-dam adjustments, and get its pre-weaning gain and weaning weight ratio within its group.

Estimate daily biogas production from cattle, pig, poultry, sheep, goat or horse manure, and size a farm biodigester from the daily load and retention time (FAO method), with energy and LPG equivalents.

Convert density between kg/m³, g/cm³ (g/mL), g/L, mg/L, t/m³, lb/ft³, lb/in³, pounds per US or UK gallon and oz/in³ — for liquids, metals, concrete and lab work.

Find the antipode of any place: the point on the exact opposite side of the Earth, in decimal degrees and DMS, plus how close any second place comes to it.

Convert latitude/longitude (decimal or DMS) to UTM zone, easting and northing on WGS 84, or UTM back to lat/long, with MGRS, scale factor and convergence.

Convert sieve mesh number to microns, mm and inches (ASTM E11 and Tyler), find the sieve for a particle size, or work out a wire cloth opening and open area.