Tech Calculators

How long a file takes to download at your connection speed — with the megabits-vs-megabytes conversion done correctly.

Convert KB, MB, GB and TB — in both decimal (1000) and binary (1024) systems — and see why a 1 TB drive shows ~931 GiB.

Calculate a display’s pixels per inch, total megapixels and dot pitch from its resolution and diagonal size.

Simplify any width and height to its aspect ratio, and scale it to a new width without distortion.

Convert any hex color code — #aabbcc or shorthand #abc — to its red, green and blue values and a ready-to-paste rgb() string.

Turn red, green and blue values (0–255) into a hex color code and a CSS rgb() string.

Estimate a random password’s entropy in bits and how long an offline attack would take to crack it — from length and character set only.

Convert a Unix timestamp to a human-readable UTC date and time — with automatic detection of millisecond timestamps.

Estimate a video file’s size from its bitrate and duration, with size comparisons for common quality presets.

Convert between Ethereum units (wei, gwei, ether) and Bitcoin units (satoshi, bit, mBTC, bitcoin) exactly, with no rounding or scientific notation.

Encode any text to Base64 or decode a Base64 string back to text — full UTF-8 support, done with the standard RFC 4648 alphabet.

Percent-encode text for safe use in URLs, or decode a percent-encoded string back to readable text — using the browser’s own encodeURIComponent.

Beautify JSON with 2- or 4-space indentation, or minify it to a single line — with a validity check and a structure summary.

Generate MD5, SHA-1 and SHA-256 hashes of any text, computed with pure standard algorithms and shown as lowercase hex.

Convert a Unix octal file mode like 755 into its rwx symbolic permissions and a plain-English breakdown for owner, group and others.

Enter an IPv4 address and CIDR prefix to get the network and broadcast addresses, subnet mask, wildcard mask, usable host range and host count.

Expand a shortened IPv6 address to its full eight-group form, or compress a full address to the canonical RFC 5952 short form.

Decode any 5-field cron expression into plain English and see the next five times it will run in your local timezone.

Convert pixels to em or rem, or em back to pixels, against any base font size — with the ready-to-paste CSS declaration.

Generate one or more random RFC 4122 version-4 UUIDs — the 128-bit identifiers used for database keys, request IDs and file names.

Count the words, characters, sentences and paragraphs in any text, plus an estimated reading time — instantly, in your browser.

Count characters with and without spaces, UTF-8 byte length, words and lines — perfect for tweets, meta descriptions and SMS limits.

Convert text to UPPERCASE, lowercase, Sentence case, Title Case (AP, Chicago, APA or MLA rules), camelCase, PascalCase, snake_case, CONSTANT_CASE, kebab-case and more — line by line, with word, character, sentence and line counts.

Convert text to binary, hexadecimal, decimal, octal or Base64 and back again — with full UTF-8 support for accents, ñ and emoji (plus UTF-16, Latin-1 and ASCII), a character-by-character byte table and auto-detection of pasted code.

Translate text into International Morse code or decode dots and dashes back to text. Handles letters, digits, punctuation, accented letters and prosigns, counts dots, dashes and timing units, and shows how long the message takes to send at any WPM, with Farnsworth spacing.

Check the WCAG contrast ratio between a foreground and background colour, and see whether it passes AA and AAA for normal and large text.

Convert a hex colour code to HSL (hue, saturation, lightness) and RGB — the CSS-ready values, with a plain-English reading of the colour.

Convert RGB colour values to HSL (hue, saturation, lightness) and the matching hex code — ready to paste into CSS.

Convert a number between any bases from 2 to 36 — binary, octal, decimal, hexadecimal and beyond — with a quick reference row for the common bases.

Convert between bytes, KB, MB, GB, TB and PB, switching between binary (1024) and decimal (1000) units — the source of the "why is my drive smaller" gap.

Turn any title into a clean, URL-safe slug — lowercase, hyphen-separated, with punctuation and accents stripped, ready for SEO-friendly links.

Rate a password by its entropy — length and character variety — and estimate how long it would take to crack by brute force.

How long a file takes to move in each direction — download and upload times side by side, with the megabit-to-megabyte conversion handled for you.

Work backwards from a target file size to the bitrate you need to encode at — the reverse of a file-size estimate, for hitting an upload or disc limit.

What a metered data plan or overage actually costs — included allowance, extra usage and the per-gigabyte rate turned into a real bill.

How much internet speed you actually need for the streams running at once — and how much data a month of watching burns through.

Turn a CIDR prefix like /24 into the numbers that matter — total addresses, usable hosts and the matching subnet mask.

Enter an IPv4 address and CIDR prefix to get the network address, broadcast, first and last usable host, and the full range.

Size the drive or cloud plan your media library needs — JPEG/HEIC and RAW photos plus video by resolution and frame rate turned into gigabytes, with growth over the years, headroom, backup copies, the size Windows shows, a drive-fit table and upload time.

Usable capacity and fault tolerance for RAID 0, 1, 5, 6 and 10 — how much of your raw disk space you actually get to use.

What "three nines" or "five nines" really allows — turn an uptime percentage into the downtime you can have per day, month and year.

Whether your image has the resolution to print sharp at a given size — the DPI you get, plus the biggest size that still hits 300 DPI.

Resize without distortion — enter an aspect ratio and one dimension, get the pixel value for the other, exactly proportional.

The hidden bill for getting data OUT of the cloud — egress charges after the free tier, per month and per year.

Measure the true strength of a random word passphrase in bits, and see how long it would take to crack.

Find the minimum password length needed to reach a target entropy for any character set.

Estimate how long a proof-of-work search takes from a hash rate and a target difficulty in leading zero bits.

Turn an API rate limit into sustainable throughput per hour and day, and the time to complete a batch of requests.

Requests per second four ways with Little's Law: a server's maximum throughput from response time and concurrency, load from concurrent users and think time, peak RPS from daily traffic, and the workers and servers needed for a target RPS — with queueing delay, headroom and bandwidth.

Work out the maximum page weight you can ship to hit a target load time on a given connection.

Estimate how long a battery takes to charge from its capacity, charger current and charging efficiency.

Estimate the total render time for an animation from its length, frame rate and time per frame.

Estimate how long a video encode will take from its length, frame rate and the encoder's throughput in frames per second.

Convert image pixel dimensions and DPI into the physical print size in inches and centimetres.

Estimate the GPU memory needed to load an AI model from its parameter count and numeric precision.

Forecast whether you'll blow through your monthly data cap based on how much you've used so far this cycle.

See how much larger a file or string becomes when Base64-encoded — the encoded byte count, the ~33% overhead and the extra bytes added.

Compare an original and compressed file size to get the compression ratio, the percentage of space saved and the bytes reclaimed.

Estimate the uncompressed size of a bitmap image from its width, height and colour bit depth — plus megapixels and total pixel count.

Work out the size of an audio file from its bitrate and duration — for MP3, AAC, streaming or podcast planning.

Estimate how long a UPS or battery bank will power a load from the battery voltage, capacity, inverter efficiency and watts drawn.

Check whether a Power-over-Ethernet switch can drive your devices — power used, budget remaining and the maximum number of ports you can power.

Voltage drop for copper or aluminum wire from 18 AWG to 1000 kcmil or 1.5–240 mm²: drop in volts and percent, voltage at the load, wire loss, minimum wire size, maximum run length and an NEC ampacity check.

Size a solar array from your daily energy use, local peak sun hours and panel wattage — the kW needed and the number of panels.

Convert between kilowatt-hours, watt-hours, megawatt-hours, joules and megajoules — energy units for bills, batteries and appliances.

Turn a screen’s diagonal and aspect ratio into its real width and height in inches and centimetres, plus the display area.

Convert characters typed and elapsed time into words per minute — gross WPM, net WPM after errors, accuracy and characters per minute.

Turn lines of code and hours worked into a productivity rate — lines per hour, per working day and per week — with the usual caveats.

Convert a frame rate (FPS) into the time each frame takes — in milliseconds and microseconds — and see how many frames fit in a second.

Turn a monitor refresh rate into its frame window in milliseconds and check whether the panel’s pixel response time is fast enough to avoid ghosting.

Compare your game’s FPS against your monitor’s refresh rate to see how many frames actually display, wasted frames and whether you should cap the frame rate.

Set a target response time, add up the latency each stage consumes (DNS, connect, server, transfer, render) and see how much of the budget is left.

Turn a packet-loss percentage into real effects: expected packets lost, delivered goodput and the chance a whole multi-packet message arrives intact.

Compute the bandwidth-delay product and the throughput a given TCP window can reach over a round trip — and the window size needed to fill the link.

Split an IPv4 network into smaller subnets: get the number of subnets created, addresses per subnet and usable hosts when moving from one prefix to another.

Count how many MAC addresses lie inclusively between a start and end 48-bit hardware address — useful for OUI blocks and address-range planning.

Estimate how long a RAID array takes to rebuild after a drive failure from the disk size and rebuild throughput — plus the window your array runs degraded.

Estimate a table’s storage from its row count, average row size and index overhead — data size, index size and total disk footprint.

Compute cache hit and miss ratios from your hit and miss counts, plus the effective average access time when hits and misses have different latencies.

Size a thread pool with Little’s law from your request rate and average processing time, adjusted for a target utilisation so the pool has headroom.

Estimate the daily and monthly profit of a mining rig from its coin revenue, power draw, electricity price and pool fee — and see the break-even point.

Work out the cost of an on-chain transaction from the gas price in gwei, the gas units used and the token price — in both native coin and dollars.

Calculate a crypto token’s market cap and fully diluted valuation from its price, circulating supply and max supply — and see how much dilution is still to come.

See how much a staked crypto balance grows over time with compounding rewards, and compare the quoted APY against a simple no-compounding return.

Estimate the cost of an LLM API call or workload from input and output token counts, per-million-token prices and the number of requests.

Check how much of a model’s context window your prompt, history and reserved output tokens use — and how much room is left for the reply.

Estimate the cost of a batch of AI-generated images from the price per image, the number of variations and how many prompts you run.

Estimate the monthly and annual cost of a cloud virtual machine from its hourly rate, how many hours it runs and the number of instances.

Estimate the monthly cost of a serverless function from its request count, execution time, memory size and the per-request and GB-second rates.

Estimate monthly CDN egress cost from your traffic — average object size, requests per month and the per-GB data-transfer rate.

Estimate the monthly cost of a pay-per-operation database from your read and write operation counts, their unit prices and stored data volume.

Work out your infrastructure cost per active user and per paying customer from total monthly API spend, user count and conversion rate.

Estimate how long an attacker needs to brute-force a password from its length, character set and the guessing speed of the attack.

Count the total number of possible passwords for a given length and character set, and see the entropy in bits.

Estimate the maximum line-of-sight WiFi range from transmit power, antenna gains and receiver sensitivity using free-space path loss.

Size the internet or network link you need for N users — from an average per user or from an activity mix (browsing, video calls, streaming, VoIP) — with download and upload, headroom, the next standard plan size, growth and monthly data.

Calculate the bandwidth a VoIP phone call needs from the codec, packet interval and header overhead — per call and across all concurrent calls.

Estimate the upload and download bandwidth each participant and the whole meeting needs for a video call at a chosen quality.

Work out how long a backup or data transfer takes from the data size, throughput, transfer efficiency and any compression — and whether it fits your window.

See the usable storage, fault tolerance and space efficiency of a RAID array by level, from the number and size of your drives.

Estimate the raw and usable (front-end) IOPS of a disk array from drive count, per-drive IOPS, RAID write penalty and your read/write mix.

Compare the total cost of ownership of on-premises hardware against a cloud subscription over several years, and see which is cheaper.

Count the days until an SSL/TLS certificate expires, flag when it enters the renewal window, and get the date you should renew by.

Turn a DNS TTL into plain time, the worst-case propagation window, how many origin lookups it causes per day and the resulting cache hit rate.

Turn a hex color code into ready-to-paste CSS rgb() and rgba() values, with each channel in decimal — 3-digit shorthand supported.

Convert screen RGB colors to CMYK ink percentages for print — cyan, magenta, yellow and key (black) from any 0–255 color.

Check text vs background contrast against WCAG AA and AAA thresholds — get the exact ratio and pass/fail for normal and large text.

Generate evenly spaced color stops between two hex colors — perfect for banding-free gradients, chart scales and tint ramps.

Convert between px, rem and em using your root and parent font sizes — the exact math the browser applies to CSS units.

Convert a pixel size into vw, vh, vmin and vmax for a given screen — responsive CSS units done without guesswork.

Work out the exact column width for a grid once gutters are subtracted — for CSS Grid, Flexbox rows and design-system layouts.

Build a modular type scale from a base font size and a ratio — golden ratio by default — with px and rem for every step.

Turn a unitless line-height ratio into pixels and leading for any font size — with a readable range for body text.

Estimate reading time from a word count at your chosen words-per-minute — for articles, scripts, speeches and content planning.

Pick the responsive image widths to export for a given layout size and device pixel ratios — build a ready srcset attribute.

Convert a number between any two bases from 2 to 36 — binary, octal, decimal, hex and beyond — with the common bases shown too.

Size the PSU for your PC build from CPU and GPU power draw plus the rest of the system, with a safety headroom so the supply runs in its efficient zone.

Turn a PC build price and its average frame rate into cost per FPS — the single number that lets you compare gaming builds on real value, not spec sheets.

Compare your GPU frame rate to your monitor refresh rate to see how much of the panel you are actually using — and whether frames are being wasted.

Add up the download speed your household actually needs from the streams, calls and devices running at once, and match it to the right internet plan.

Estimate how many mesh WiFi nodes your home needs from its floor area, number of floors and wall construction — so you cover every room without dead zones.

Plan how much NAS storage your photo and video library will need over years, including RAID redundancy overhead, so you buy the right drives once.

Work out the storage a 3-2-1 (or 3-2-1-1-0) backup plan needs: copies, version history or a daily/weekly/monthly retention schedule, compression and dedup, data growth, drive sizes, cloud cost and upload time.

Size an off-grid solar array and battery bank from your daily energy use, local sun hours and days of autonomy — the two numbers that make or break a standalone system.

Find the breaker size and circuit amps your home EV charger needs under the 125% continuous-load rule, plus the real charging power it delivers.

Add up the always-on power your smart home devices draw and see the yearly kWh and running cost — the phantom load of hubs, plugs, cameras and speakers adds up.

Work out how many batteries a drone mission needs and how many swaps you will make — from total flight time, each pack's rated minutes (or mAh and current draw), landing reserve, wind and cold — plus spares, field-charging rotation, a flight-by-flight plan and the airline Wh limit.

Estimate how far an e-bike can go on a charge from its battery voltage, capacity and your real-world energy use per mile or kilometre.

Estimate YouTube AdSense earnings from monthly views and your RPM — the amount you actually keep per 1,000 views after YouTube’s cut.

Turn subscriber count, monthly price and platform fees into your real recurring revenue — MRR, annual run-rate and net-of-churn take-home.

Estimate podcast sponsorship income from downloads per episode, ad slots and CPM — the standard cost-per-1,000-downloads pricing model.

Price a newsletter ad from your list size, open rate and CPM — what one sponsored placement is worth per send and per month.

Estimate a fair sponsored-post rate from your follower count and engagement — a benchmark range for negotiating brand deals.

Estimate TikTok Creator Fund / Creativity Program payouts from your monthly views — and see why views alone earn so little.

Add up your Twitch income from subscriptions, bits and tips — with the platform split applied so you see what you actually keep.

Work out your Amazon KDP ebook royalty per copy and total earnings — including the 70% tier’s delivery-cost deduction.

Estimate net revenue from an online course after platform fees and refunds — and see the take-home per enrolled student.

Add up recurring revenue across three membership tiers — MRR, annual run-rate and average revenue per member after platform fees.

Find how many sales a digital product needs to cover its upfront cost — accounting for platform fees and per-sale processing.

Estimate how much display-ad revenue your site loses to ad blockers — the gap between blocked pageviews and what you could be earning.

Turn a training run — number of GPUs, wall-clock hours and price per GPU-hour — into total GPU-hours and dollar cost, the way cloud accelerator bills are actually rated.

See how many LLM tokens a dollar buys at a given per-million-token price, plus how many tokens your monthly budget covers — the fastest way to compare model pricing.

Estimate what a fine-tuning job costs from your dataset size, epochs and the provider’s per-million-token training rate — the tokens-processed model most APIs bill on.

Work out how much disk or RAM a set of embeddings needs from the vector count, dimensionality and numeric precision, including index overhead.

Estimate the monthly cost of a managed vector database from stored vectors, dimensions and query volume — storage plus per-query charges combined.

Break an LLM response time into time-to-first-token plus generation time, and check it against your target latency budget.

Estimate the activation memory a training batch consumes from batch size, sequence length, hidden size and layer count — the term that scales with batch and blows up GPU memory.

See how much memory a model’s weights need at each precision — fp32, fp16, int8 or int4 — plus runtime overhead, from just the parameter count.

Estimate what annotating a training dataset costs from item count, labels per item, price per label and a QA/review overhead — plus the cost per finished item.

Find the real return on a rented or owned GPU: how idle time inflates your effective cost per productive hour, and whether the revenue it earns beats the bill.

Estimate how much prompt caching saves when a long shared prefix (system prompt, context, docs) is reused across many requests, at the provider’s cache discount.

Work out how many chunks a document corpus splits into for a RAG pipeline given chunk size and overlap, plus the tokens embedded and the one-time embedding cost.

Estimate the on-disk size of a Git repository from its working tree and commit history, so you can plan clone times and storage.

Estimate the monthly cost of your CI/CD pipeline from build frequency, duration, parallelism and any free-tier minutes.

Estimate the egress bandwidth and cost of pulling a container image across your fleet, and see what a local cache saves.

Estimate the daily and monthly cost of log ingestion and retention from your log volume, retention window and per-GB pricing.

Turn a service-level objective into an error budget: how much downtime you can spend per month, week and day before you breach the SLO.

See how a follow-the-shift on-call rotation spreads across your team: your share of hours, weeks between shifts and hours per shift.

Quantify what your mean time to resolve costs the business, and how much money faster recovery would save each month and year.

Turn a feature-flag rollout percentage into real user counts, and preview a staged ramp from canary to full launch.

Estimate how many days an A/B test needs to run to collect its required sample, from your daily traffic, variant count and allocation.

Model a single-server queue with the M/M/1 formulas: utilisation, average wait time and queue length from arrival and service rates.

Size a token-bucket rate limiter: sustained throughput, burst capacity and how long a full bucket lasts under a given request rate.

Build an exponential backoff retry schedule for webhooks or API calls, with per-attempt delays, a max cap and total elapsed time.

Find the physical length of a quarter-wave, half-wave or full-wave antenna for any frequency, with the velocity factor built in.

Pick a radio band — FM, AM, Wi-Fi, CB, LTE — or enter any frequency to get its wavelength, half-wave and quarter-wave lengths.

Convert dBm to milliwatts and watts (or watts back to dBm) — the decibel power scale used across RF, Wi-Fi and fibre.

Convert antenna gain in dBi to a linear gain, EIRP and the theoretical range improvement over an isotropic antenna.

Calculate total signal loss through a coax feedline from its attenuation rating and length, and see how much power reaches the antenna.

Size the current-limiting resistor for an LED from the supply voltage, LED forward voltage and desired current — with the nearest standard value.

Compute the output frequency, period and duty cycle of a 555 timer in astable mode from R1, R2 and the timing capacitor.

Find the voltage gain of an inverting or non-inverting op-amp from its feedback and input resistors, in V/V and decibels.

Calculate the output voltage of a two-resistor voltage divider, plus the current it draws and the power it dissipates.

Find the cutoff frequency of a simple RC low-pass filter from the resistor and capacitor, plus its time constant and −3 dB point.

Work out the pack voltage, capacity and energy when you wire cells in series and parallel — the SxP configuration for any battery build.

Estimate how long a hand-soldering job will take from the joint count, seconds per joint, setup time and a rework allowance.

Work out what a 3D print costs in filament from the model weight, spool price and spool size — including waste for supports, brim and purge.

Estimate how many layers a 3D print has and roughly how long it will take from the model height, layer height and average time per layer.

Turn spindle RPM, flute count and chip load into a CNC feed rate, and get the cutter surface speed for milling and routing.

Estimate how long a raster laser engraving takes from the area, line spacing, head speed and pass count.

Find the minimum PCB trace width for a given current and temperature rise using the IPC-2221 formula, for external or internal copper layers.

Size a heat sink by finding the maximum sink-to-air thermal resistance that keeps a component below its junction temperature limit.

Estimate the airflow in CFM a PC or electronics case needs to hold a target temperature rise, and how many fans it takes.

Find the maximum PoE cable run before voltage drop starves the device, from the source voltage, load current and conductor resistance.

Check whether a fiber link works: compare the transmitter power budget against fiber, connector and splice losses to find the margin.

Estimate the extra read time fragmentation costs on a spinning hard drive from the file count, fragments per file and seek time — and why SSDs are exempt.

Estimate how much RAM your workload needs — OS, apps, browser tabs, games, streaming, photo and video editing, virtual machines and local AI models — plus headroom, then see the next standard size, the module kit to buy, how loaded your current RAM is and the cost.

Check whether a monitor fits a gas-spring or mechanical arm — comparing its weight against the arm’s minimum and maximum load range.

Estimate how many printed pages a manuscript will fill from its word count, trim size, font size, line spacing and margins — with chapter openings, part pages, images, even or signature rounding, spine width, print cost and a page count for every common trim size.

Calculate a paperback or hardcover spine width from page count and paper stock — the measurement your cover template depends on.

Turn a trim size into the full bleed document size and the safe printable area — so nothing important gets cut off at the guillotine.

Estimate the real ink cost per page and per job from your cartridge yield, price and how much ink your artwork actually lays down.

Convert paper weight in GSM to the US basis weight in pounds for any grade — because a 20 lb bond and an 80 lb text can weigh almost the same.

Work out how many pages fit on a press sheet and how many sheets a job needs — the core of any imposition and paper estimate.

Find how many signatures a booklet needs, plus the blank pages you must pad to fill the last one — essential for perfect-bound and section-sewn jobs.

See how many business cards fit on a sheet with your margins and gutters, and how many sheets a print run needs.

Check the effective PPI of an image at a given print size and find the largest size it can print sharply — before you send it to a large-format printer.

Work out how many grommets a vinyl or mesh banner needs and the exact even spacing on each edge: all four edges, top and bottom, top only, sides or corners, with a measured position list for marking, counts at other spacings, ties or bungees and grommet cost for several banners.

Estimate the length of vinyl roll a batch of decals needs, including gutters and waste — so you order the right amount the first time.

Split a print job into fixed setup and per-unit cost to find the true cost per piece — and see how much a bigger run drives it down.

Predict how loud a speaker is at any listening distance from its 1 W / 1 m sensitivity and the power you feed it, using the inverse-square law.

Work out how many watts of amplifier power you need to hit a target loudness at a given distance, including crest-factor headroom for peaks.

Calculate the length of a round vent for a ported subwoofer box from the enclosure volume, tuning frequency and port diameter.

Find the axial room modes — the standing-wave frequencies where bass builds up or cancels — from your room length, width and height.

Estimate a room’s reverberation time with the Sabine equation from its volume, surface area and average absorption coefficient.

See how much the sound level changes when you move a microphone nearer or farther from a source, using the inverse-square law.

Find the gain to apply so your loudest peak lands on a target level, and see how much digital headroom you keep below 0 dBFS.

Calculate the gain needed to match your track’s integrated loudness to a streaming target like −14 LUFS, and check the resulting true peak.

Convert an audio clip’s duration into total samples and uncompressed PCM file size from the sample rate, bit depth and channel count.

Estimate how long an export will take from your timeline length, frame rate and how many frames per second your machine can render.

Estimate the disk space a set of editing proxies will use from your footage duration and the proxy bitrate, and compare it to the originals.

Estimate the video bitrate a streaming quality needs from resolution, frame rate and a bits-per-pixel quality factor for your codec.

See how much money and energy you save each year by swapping an incandescent or halogen bulb for a smart LED — per bulb and across the whole house.

Estimate how long a home battery (Powerwall-style) will run your house or a critical-loads panel during an outage, from usable capacity and your load.

Work out what share of your solar production you actually use on-site (self-consumption) versus export, and how much of your home use it covers (self-sufficiency).

Estimate your monthly net metering bill: value of exported solar, cost of imported grid power, and the net credit or amount owed.

Compare the annual heating cost of an electric heat pump against a gas furnace, using each fuel price and the heat pump’s seasonal efficiency (COP).

Check whether your electrical panel can handle an EV charger: continuous circuit load, the 80% code limit, and remaining spare capacity.

Size a whole-home surge protective device (SPD): the surge-current rating and joule headroom to aim for based on your service and exposure.

Estimate how many days of footage your security cameras will hold on a given drive, from resolution, bitrate, camera count and recording mode.

Add up the total network bandwidth your IP cameras push to an NVR, and check it against your switch or NIC capacity with headroom to spare.

Estimate the heating and cooling savings from a smart thermostat schedule, based on how many degree-hours of setback it applies each day.

Figure out how many water leak sensors you need to protect your home’s at-risk spots, and the gap between what you have and full coverage.

Estimate how many mesh Wi-Fi nodes cover your home, adjusting per-node reach for building materials, floors and interference.

Estimate your monthly and yearly hosting bill from page views, average page weight, the bandwidth your plan includes and its overage price. Adds bot traffic, CDN offload and traffic growth, shows the page views you can serve before overage, cost per 1,000 views and a comparison with per-GB CDN pricing.

Set a performance budget for your web page from a target load time and connection speed, then check whether your current asset sizes fit inside it.

Check LCP, INP and CLS against Google’s good/needs-work/poor thresholds and see how much headroom you have before a metric slips into the next tier.

See how many bytes you save per page and per month by compressing or converting images to a modern format like WebP or AVIF, plus the bandwidth cut.

Estimate monthly video hosting and delivery costs from views, average watch time, bitrate and storage — the streaming bandwidth is what drives the bill.

Plan a sending warmup for a new domain or IP: ramp daily volume gradually to build reputation and see how many days it takes to reach your target.

Estimate how long a DNS change takes to propagate worldwide from your record’s TTL, and see the safe wait before you can rely on the new value everywhere.

Compare the multi-year cost of a paid SSL/TLS certificate against a free automated one like Let’s Encrypt, including your setup and renewal labour.

Total up the yearly and multi-year cost of keeping your domains registered, including privacy protection and any premium renewals, across a whole portfolio.

See how a CDN cache hit ratio cuts origin bandwidth and cost: the higher the hit rate, the less traffic reaches your server and the smaller your egress bill.

Estimate the on-disk size of a B-tree index from row count, the width of the indexed columns and per-entry overhead — before you add it and watch storage grow.

Work out how many pages and API requests it takes to fetch a dataset at a given page size, plus the total time once you account for per-request latency.

Calculate a screen’s pixel density (PPI) from its resolution and diagonal size — or the diagonal from the resolution and PPI, or PPI from the width and height — with dot pitch, aspect ratio, physical size, retina viewing distance and a comparison with popular phones, laptops, monitors and TVs.

Convert an uptime SLA percentage into the allowed downtime per day, week, month and year.

Convert RAM CAS latency and speed into true access latency in nanoseconds.

Find how many total and usable IPv4 addresses a subnet prefix provides, plus its mask.

Check the WCAG 2.2 contrast ratio of any text and background color (hex, rgb, hsl or color name, with transparency): AA and AAA for normal and large text, 3:1 for UI components, the nearest passing color and an optional APCA Lc (draft) score.

See how much bandwidth compression saves from the original and compressed file sizes.

Find the largest quality print size for an image at a given DPI, in inches and centimetres.

Estimate the file size of an audio or video clip from its bitrate and length.

Estimate how long a battery lasts from its capacity, the device’s current draw and efficiency.

Size a solar battery bank from daily energy use, days of autonomy, depth of discharge, battery chemistry, inverter efficiency and temperature — amp-hours, kWh, series/parallel layout, how many batteries, real autonomy and the solar array to recharge it.

Throw distance for a given screen size and projector throw ratio — or the screen width you get at a set distance — with short-throw and ultra-short-throw ranges, aspect ratio and lens shift notes.

Hard-drive capacity for a security camera system — cameras, resolution and codec (H.264, H.265, smart codecs), frame rate, scene activity, recording hours, motion share and retention days — or how many days your drives hold, with RAID drive counts, NVR bandwidth and retention tables.

QR code version (21×21 to 177×177 modules) and character capacity for your data length, mode and error-correction level — with the minimum print size for a given scanning distance.

Capacitor and inductor values for a passive two-way speaker crossover — 1st-order 6 dB or 2nd-order 12 dB Butterworth and Linkwitz-Riley — from crossover frequency and woofer/tweeter impedance.

Voltage, current and power a headphone needs for a target loudness from its impedance and sensitivity (dB/mW or dB/V) — does your phone, DAC dongle or amp have enough headroom?

Size a power inverter from the appliances you will run — continuous watts, surge watts for motors and compressors, power factor and efficiency — with DC input current, fuse and battery-cable sizing.

Series resistor for a Zener voltage regulator from input voltage range, Zener voltage and load current — resistor value and power rating, Zener power dissipation and minimum load conditions.

Resistor values for an LM317 / LM117 adjustable regulator — output voltage from R1 and R2, or R2 for a target voltage — with dropout, power dissipation, heatsink need and constant-current mode.

Pulse-width modulation duty cycle from on/off times or frequency and pulse width — average voltage, RMS voltage, timer compare values for 8/10/12/16-bit MCUs, and LED dimming perception.

Temperature from an NTC thermistor’s resistance using the beta (B) parameter equation — or resistance at a temperature — with voltage-divider ADC readings, sensitivity and Steinhart-Hart comparison.

Steps per millimetre for belt-driven and leadscrew axes and for extruders — motor step angle, microstepping, pulley teeth and belt pitch or screw lead, gear ratio — with resolution and the calibration correction formula.

Size a single- or three-phase transformer from load kW and power factor, amps or kVA: required kVA with demand factor, growth and altitude derating, the next standard ANSI or IEC rating, full-load currents, NEC 450.3 overcurrent limits, fault current and motor-starting voltage dip.

Mean time between failures, mean time to repair and inherent availability from operating hours and failure counts — failure rate, reliability over a mission time, expected failures per year and the “nines” of uptime.

Maximum line-of-sight distance between two antennas from their heights — optical horizon and the 4/3-earth radio horizon, the height needed to reach a given distance, and the bulge of the Earth in the middle of the path.

First Fresnel zone radius at any point along a microwave or Wi-Fi link from frequency and path length, the 60% clearance rule, Earth bulge, and the total obstacle clearance needed at mid-path for a reliable point-to-point link.

Free-space path loss in dB from distance and frequency, the received power for a given transmit power and antenna gains, wavelength, and how loss changes with doubling distance or frequency — for Wi-Fi, LoRa, cellular, satellite and microwave links.

Complete point-to-point link budget: transmit power, cable and connector losses, antenna gains, free-space path loss, extra losses and receiver sensitivity — received signal, fade margin, availability estimate and the maximum range at your target margin.

Effective isotropic radiated power and effective radiated power from transmitter power, feedline loss and antenna gain (dBi or dBd) — in dBm and watts, the conversion between EIRP and ERP, and a check against common regulatory limits.

Convert between VSWR, return loss, reflection coefficient and mismatch loss from any one of them or from forward and reflected power — percentage of power reflected, power actually delivered, the impedance range a given VSWR implies, and typical acceptance limits.

Check a subtitle or caption against reading-speed limits — characters per second and words per minute from text and on-screen duration, the minimum duration for the text, maximum characters for a given duration, line-length limits (Netflix 42, BBC 37) and whether to split or condense.

Synchronous speed of an AC induction motor from supply frequency and pole count, slip percentage from the nameplate or measured rpm, rotor frequency, speed at any load or frequency (VFD), and torque from horsepower at the actual speed.

Capacitor kVAR needed to raise a load’s power factor from its present value to a target, the reduction in apparent power and line current, released transformer capacity, capacitance in microfarads per phase, and the utility penalty saved.

Energy and cost saved by controlling a centrifugal fan or pump with a variable-frequency drive instead of a damper, valve or on/off cycling — affinity-law power at each speed, annual kWh from a duty-cycle profile, drive losses, payback and CO₂.

Available fault current at a transformer secondary from kVA, voltage and impedance (%Z), with the infinite-bus value and the reduction from a finite primary source, the fault level at the end of a feeder, and the interrupting rating your breakers need.

Locked-rotor (inrush) current of a motor from its horsepower and NEMA code letter or LRC multiple, the voltage dip during starting for a given source and cable impedance, the effect of soft starters, wye-delta and VFDs, and whether the dip stays within limits.

How much longer (or shorter) translated text gets by target language and string length — expansion factors for German, French, Spanish, Russian, Finnish, Japanese, Chinese, Arabic and more, the UI width to reserve, character limits for buttons and labels, and pseudo-localization padding.

Match halftone screen ruling (LPI) to output resolution and image resolution: grey levels available from DPI ÷ LPI, the image PPI needed (2× rule) for a print size, scaling limits of a photo, dot gain expectations and LPI recommendations by press and paper.

Convert SMPTE timecode to a frame count and back at any frame rate — 23.976, 24, 25, 29.97 drop-frame and non-drop, 30, 50, 59.94, 60 fps — with the real elapsed time, the drop-frame correction explained, duration between two timecodes, and frames-to-seconds for subtitles and edits.

Calculate the length of a half-wave dipole, each leg, a quarter-wave vertical or a full-wave loop for any frequency — the 468/f and 143/f formulas with end-effect and wire velocity factor, inverted-V shortening, band presets for HF, VHF, UHF, FM broadcast and CB, in metres, feet and inches.

Calculate audio file size from duration, sample rate, bit depth and channels for uncompressed WAV/AIFF, estimate FLAC and lossy MP3/AAC sizes from bitrate, see megabytes per minute and per hour, and how many songs, podcast episodes or hours fit on a card or drive.

Calculate the delay in milliseconds (and samples) to time-align speakers — PA delay towers and fills to the main stack, home-theatre speaker distances, or a subwoofer to the mains — from the distance difference and air temperature, with the Haas-effect offset for fill speakers and the distance one millisecond represents.

Size an injection molding press — clamp tonnage from projected area, cavities, runner and material (PP, PE, ABS, PC, nylon, PMMA), plus cooling time from wall thickness and thermal diffusivity, the full cycle time, shot weight, parts per hour and the machine's shot-capacity check.

Design an interference (shrink or press) fit — contact pressure from the diametral interference, hub and shaft dimensions and moduli, torque and axial-force capacity from friction, hub hoop stress against yield, the temperature to heat the hub (or cool the shaft) for assembly, and the press force for a press fit.

Spur-gear geometry from module (or diametral pitch) and tooth counts — pitch, outside, root and base diameters, addendum and dedendum, center distance, gear ratio, circular pitch and tooth thickness, output speed and pitch-line velocity, plus the interference check for small pinions and the module ↔ DP conversion.

Work out roller-chain length in pitches and links for two sprockets and a centre distance (ANSI #25–#120, ISO 06B–24B), round to an even link count, get the exact centre distance for that chain, sprocket pitch diameters, chain speed and the wrap angle on the small sprocket — plus the recommended centre-distance range.

Torque to raise and lower a load with an ACME, metric trapezoidal, square-thread or ball screw — efficiency, self-locking check, collar friction, motor power and torque with acceleration, linear speed, critical speed and buckling load, in N·m and lbf·in.

Wire several speakers to one amplifier safely: total impedance for series, parallel and series-parallel combinations, whether it meets the amplifier's minimum load, the power the amp delivers at that load and how it splits per speaker, the safe amplifier size for the speakers' ratings, and which wiring to choose for 2, 3, 4, 6 or 8 speakers or a guitar cabinet.

Pick the speaker cable gauge for a run: resistance of the round trip, power lost in the cable as a percentage and in dB, the effect on damping factor and frequency response, the maximum run for each AWG at 4 Ω or 8 Ω under the 5% rule, and a metric mm² equivalent — for home hi-fi, in-ceiling runs, PA snakes and 70 V systems.

Size a PA for an event: the sound level the audience needs by content (speech, acoustic, worship, DJ, rock), power in watts from the audience size and venue (indoor or outdoor), the SPL at the back row from speaker sensitivity and distance, how many tops and subwoofers, delay towers for deep crowds, and a sanity check on your existing rig.

Add up a lighting rig: watts and amps for tungsten, LED and moving-head fixtures at 120 V or 230 V, fixtures per dimmer channel, non-dim circuits packed fixture by fixture with the 80% rule, amps on each phase of a three-phase feed, feeder and generator size, DMX channels, universes and lines, cable size and heat load.

Plan DMX addressing for a rig: enter fixture groups with their channel footprint and count to get start addresses for every fixture, the universes needed, channels used and spare, a tidy "round to 10" addressing option, universe splits by position, and the dip-switch or 9-bit binary settings for old fixtures.

Find out which part is holding your frame rate back using numbers from your own overlay — average GPU usage, CPU usage, current FPS and resolution — instead of a parts database: whether you are CPU-bound or GPU-bound and by how much, the FPS you would gain from a faster GPU or CPU, what upscaling or a resolution change will do, and whether a higher-refresh monitor or a new part is the better buy.

How long will an SSD last? From its rated terabytes written (TBW) or DWPD, its capacity and your daily writes — with write amplification — get the projected years of life, the drive-writes-per-day equivalent, how much endurance the drive has already used from its SMART data, the wear from heavy workloads like video editing, databases or Chia plotting, and when to plan a replacement.

How many pods fit on a node and how many nodes does a deployment need? From node CPU and memory, system and kubelet reservations, DaemonSet overhead and your pod requests, get pods per node (the binding resource), nodes for N replicas with headroom, wasted capacity from bin-packing, requests-vs-limits ratio, and monthly cost per pod and per replica.

Size the power stage of a step-down (buck) DC-DC converter: duty cycle from input and output voltage, inductor value for a chosen ripple current, peak and RMS currents, output capacitance and ESR for a target ripple voltage, input capacitor and RMS current, and the switching-frequency trade-offs.

Convert between amps and C-rate for any battery, estimate charge time including the constant-voltage tail for lithium cells, discharge runtime at a given current or power with rate losses, and check the current against safe continuous limits for Li-ion, LiFePO₄, NiMH and lead-acid.

Pick the base resistor for an NPN or PNP transistor used as a switch: base current for hard saturation from collector current and minimum hFE with an overdrive factor, the nearest E24 resistor, the current drawn from the microcontroller pin, transistor and resistor power, and when to switch to a MOSFET or Darlington.

Check a MOSFET as a low-side switch or PWM driver: gate charge current and switching time from the gate resistor and driver, conduction loss from Rds(on) and duty cycle, switching loss at your frequency, gate-drive power, and the junction temperature for the package with or without a heatsink.

Work out an analog-to-digital converter's step size in millivolts from bits and reference voltage, the ideal SNR and quantization noise, the effective number of bits once your circuit's noise is included, the oversampling needed for extra bits, and what one count means in your sensor's units.

Size the power supply for 12 V or 24 V LED strip from watts per metre and length with headroom, estimate the voltage drop along the strip and how many power-injection points keep the far end bright, choose the feed wire gauge for the run from the supply, and check dimmer and connector current limits.

Check whether a linear voltage regulator (7805, LM317, LDO) will survive: power dissipated from input-output drop and current, efficiency, junction temperature for the package with or without a heatsink, the heatsink thermal resistance required, dropout margin, and how a buck converter or series pre-drop would compare.

Find the nearest standard resistor values in the E12, E24 and E96 series to any calculated resistance with the percentage error, the best series or parallel pair of E24 resistors to hit the target more closely, and the tolerance band that makes the effort worthwhile.

Choose the two external capacitors for a Pierce crystal oscillator from the crystal's specified load capacitance and the board's stray capacitance, then check drive level against the crystal's maximum, the oscillator gain margin from ESR and shunt capacitance, the frequency pull per picofarad, and when to add a series resistor.

Decode 4-, 5- and 6-band resistor color codes into resistance, tolerance range and temperature coefficient — or enter a resistance and get the color bands to look for, per IEC 60062.

Decode surface-mount resistor markings — 3-digit (472), 4-digit (4701), R-notation (4R7) and EIA-96 codes (01C) — into ohms, or find the SMD codes for any resistance value.

Decode ceramic and film capacitor markings such as 104, 473J, 4R7 or 2n2 into pF, nF and µF with the tolerance letter — or turn a capacitance into its 3-digit capacitor code.

Read the color bands on axial inductors (chokes) and get the inductance in µH, mH and nH with the tolerance range — or find the bands for a given inductance value.

Convert a signed decimal number to two's complement binary (4 to 32 bits) with the invert-and-add-one steps, one's complement, sign-magnitude and hex — or decode a two's complement binary back to decimal.

Convert binary to Gray code, Gray code to binary, or decimal to Gray code (up to 64 bits) with the XOR rule, and see the full reflected Gray code sequence for small bit widths.

Convert decimal numbers to binary-coded decimal (8421 BCD) and Excess-3, digit by digit, compare with pure binary, or decode a BCD bit string back to decimal and catch invalid nibbles.

Convert a decimal number to IEEE 754 single (32-bit) or double (64-bit) precision: sign, exponent and fraction bits, hex, the exact stored value and the rounding error — or decode hex bits back to decimal.

Apply bitwise AND, OR, XOR, NAND, NOR, XNOR, NOT and left/right shifts to decimal, hex or binary numbers in 8, 16 or 32 bits, with every operand and the result shown in binary, hex and decimal.

Encode data bits into a Hamming code (7,4), (15,11) or any length with parity bits at positions 1, 2, 4, 8…, optionally extended SECDED — or check a received codeword, find the syndrome and correct a single-bit error.

Estimate how much air and money compressed-air leaks waste: flow through each hole from pressure and diameter, compressor power, energy and yearly cost — the US DOE orifice method.

Chiller cooling capacity in tons of refrigeration, kW and Btu/h from chilled-water flow and supply/return temperatures (tons = gpm × ΔT ÷ 24), with glycol correction, power input and COP.

Size a compressed air receiver tank to cover peak demand during a pressure drop: V = t × Q × Pa ÷ (P1 − P2), the next standard tank, how long it lasts and the rule-of-thumb sizes for your compressor.

Check an O-ring groove design: compression (squeeze) %, gland fill %, ID stretch and the cross-section reduction from stretch, against typical static and dynamic seal design ranges.

Percent voltage unbalance of a three-phase supply from the three line voltages (NEMA MG-1 and IEC negative-sequence methods), motor derating factor and the extra winding temperature rise.

Transformer efficiency at any load from kVA rating, power factor, no-load (core) loss and full-load copper loss — the load for maximum efficiency, all-day efficiency and the energy lost per year.

Valve flow coefficient Cv and Kv for liquids from flow rate, pressure drop and specific gravity — plus the valve size to select and the flow through it at other pressure drops.

Fan shaft power and motor size from airflow and total pressure (bhp = cfm × in.wg ÷ 6356η): air power, motor input, specific fan power, yearly energy and running cost.

Validate a number with the Luhn (mod 10) checksum or generate its check digit — used on credit cards, IMEI and many ID numbers — with the doubling step by step.

Encode or decode text with the Caesar cipher (shift cipher, ROT13): choose the shift, keep punctuation, and see every possible shift to crack an unknown key.

Convert text to ASCII codes in decimal, hexadecimal and binary, or turn a list of ASCII codes back into text — with a character-by-character table and Unicode code points.

Cosine similarity of two vectors or embeddings — the cosine, the angle between them, cosine distance, dot product, both norms and the Euclidean distance.

Softmax of a list of logits with optional temperature — the probability of each class, the top class, log-sum-exp and the entropy of the distribution.

TF-IDF score of a term in a document — term frequency, inverse document frequency and their product, with raw, relative, log and binary TF and standard, smooth or probabilistic IDF.

Convert internet and transfer speeds between Mbps, Gbps, kbps and MB/s, GB/s, KB/s, MiB/s: 100 Mbps = 12.5 MB/s. Also shows data per hour and the time to move 1 GB.

Convert an IPv4 address to binary, hexadecimal and a 32-bit decimal integer — or binary back to dotted decimal — with the address class, private/public type and octet-by-octet breakdown.

Convert font sizes between points and pixels (12 pt = 16 px at the CSS 96 DPI), plus millimetres, inches, picas and em, with a chart of common point sizes at any DPI.

Convert Android density-independent pixels (dp) to physical pixels (px) and back for every density bucket — mdpi, hdpi, xhdpi, xxhdpi, xxxhdpi — with the same size in iOS points.

Compare two TVs, monitors or phones with different diagonals and aspect ratios: width, height, area, how much bigger one really is, and the 16:9 size with the same height.

Estimate how many GB of mobile data you use per month from daily hours of browsing, social media, video streaming, music, video calls and gaming — and the data plan size that fits.

How many times will a power bank charge your phone? Convert the power bank’s mAh at 3.7 V and the phone’s mAh to watt-hours, apply real conversion losses and get full charges and top-ups.

Convert battery capacity between mAh and watt-hours (Wh = mAh × V ÷ 1,000) and check the airline power bank limits: up to 100 Wh in carry-on, 100–160 Wh with approval.

Count SMS characters and segments: 160 per message in GSM-7, 70 in Unicode, 153/67 per part when split. See which characters (emoji, á, í, ó, ú) switch your text to Unicode.

Apply Amdahl's law: the speedup from running the parallel part of a program on N processors or cores, the speedup limit, parallel efficiency, time saved and Gustafson's scaled speedup.

Find the Nyquist frequency of a sampling rate, the minimum sampling rate for a signal, and the alias frequency a too-high signal folds down to, with the Nyquist zone and oversampling ratio.

Calculate the UART baud rate divisor for a microcontroller clock, the actual baud rate, the baud rate error %, the AVR UBRR value, bit and frame time, and the error for every common baud rate.

Calculate the minimum and maximum I2C pull-up resistor for SDA and SCL from the supply voltage, bus speed mode and bus capacitance (NXP UM10204), plus a suggested standard value and its rise time.

Calculate the output pulse width of a 555 timer in monostable (one-shot) mode from R and C (t = 1.1RC), or the resistor needed for a target delay, with the nearest standard value.

Design a boost (step-up) converter: duty cycle, inductor value and ripple, peak switch current, input current and minimum output capacitor from input/output voltage, load current and frequency.

Calculate the probability of a hash or ID collision (birthday bound) for any hash size in bits — CRC-32, 64-bit IDs, UUID v4, MD5, SHA-256 — and how many items give a 50% or one-in-a-billion chance.

Calculate the theoretical peak FLOPS (GFLOPS, TFLOPS) of a CPU or GPU from cores, clock speed and FLOPs per cycle, the sustained rate at a given efficiency, and how long a workload takes.

Design an L-network to match a source resistance to a load resistance at any frequency: loaded Q, series and shunt reactance and the inductor and capacitor values for low-pass or high-pass versions.

Calculate the characteristic impedance of a PCB microstrip trace from trace width, dielectric height, copper thickness and εr (Hammerstad–Wheeler and IPC-2141), plus effective permittivity and delay.

Calculate the resistor values of a Pi or T resistive attenuator pad for any attenuation in dB and impedance (50 Ω, 75 Ω, 600 Ω), with voltage and power ratios and a table of common pads.

Calculate the total noise figure, noise temperature and gain of up to four cascaded RF stages (LNA, filter, mixer, IF amplifier) with the Friis formula, stage by stage.

Calculate a radio receiver's thermal noise floor (kTB, −174 dBm/Hz), noise floor with noise figure and sensitivity in dBm, watts, microvolts and dBµV from bandwidth, noise figure and SNR.

Calculate the maximum error-free data rate of a channel with the Shannon–Hartley theorem from bandwidth and signal-to-noise ratio (dB or linear), plus spectral efficiency and Eb/N0.

Calculate peak RAM bandwidth in GB/s from the data rate (MT/s), bus width and number of memory channels — DDR4, DDR5, LPDDR and GDDR — with GiB/s, per-channel bandwidth and common configurations.

Calculate the blocking probability (grade of service) of phone lines, SIP trunks or channels with the Erlang B formula, the carried and lost traffic, and how many lines a target GoS needs.

Size the smoothing capacitor after a bridge, centre-tap or half-wave rectifier from load current, mains frequency and allowed ripple, with peak and average DC voltage and voltage rating.

Split an IPv4 network into variable-length subnets (VLSM) for a list of host requirements: network address, prefix, mask, usable range and broadcast of each subnet, plus space used and left.

Find the summary route (supernet) that covers a list of IPv4 networks, its mask and wildcard, how many extra addresses it includes, and the smallest exact set of aggregated CIDR blocks.

Calculate an IPv6 network from an address and prefix length: compressed and expanded network, first and last address, total addresses, address type, and the subnets (e.g. /64s) it can be split into.

Split a total current between two or three parallel resistors with the current divider rule: branch currents, share of the total, equivalent resistance, voltage across the branches and power in each resistor.