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§ · free tool
Unit converter. Exact factors, live results.
Convert across 8 categories — length, weight, temperature, area, volume, speed, digital storage and time — live as you type, entirely in your browser. Nothing is uploaded, and it works offline.
A free online tool by Digital HeroesCalculated locally — nothing is sent anywhere.
Common length conversions
Quick referenceAccurate conversions, fully offline
Every factor here is exact (the inch is defined as 25.4 mm, a mile as 1609.344 m, and so on), and temperatures use the proper offset formulas — not naive multiplication. It all runs in your browser, so it works on a plane with no signal and never sends a thing. Type in either field: the converter is two-way, so entering an output value recalculates the input.
§ 02 · what you can do
Eight categories, one converter.
LengthMillimeters to nautical miles — mm, cm, m, km, inches, feet, yards and miles, all from exact defined factors.
Weight & massMilligrams, grams, kilograms, tonnes, ounces, pounds, stone, and US or imperial tons.
TemperatureCelsius, Fahrenheit and Kelvin using correct offset formulas, not naive multiplication.
Area, volume & speedAcres, hectares, US cups, gallons, knots, km/h, mph and more — kitchen to cockpit.
Digital storage & timeBits, bytes, KB/MB/GB/TB and their binary KiB/MiB/GiB/TiB cousins, plus milliseconds to years.
Two-way conversionType in the output field to reverse-convert, or hit swap to flip units and carry the result over.
§ 03 · how to use it
Four steps, no manual.
- Pick a category from the tabs — Length, Weight, Temperature, Area, Volume, Speed, Digital storage or Time.
- Type a value in the From field and choose your source unit from the dropdown.
- Choose your target unit in the To dropdown — the result appears instantly, with a plain-English readout below.
- Use the swap button to reverse direction, or type directly in the result field to convert the other way.
§ 04 · faq
Frequently asked questions.
Is the Unit Converter free?
Yes — completely free for everyone. No sign-up, no account and no usage limits.
Is it private? Is my data uploaded anywhere?
No upload, ever. Every conversion is calculated in your browser on your own device — the numbers you type never leave your computer.
Does it work offline?
Yes — once the page has loaded, all the math runs locally, so it keeps converting with no connection at all.
How accurate are the conversions?
Every factor uses the exact defined value — 1 inch = 25.4 mm, 1 mile = 1609.344 m, 1 pound = 0.45359237 kg. Temperatures use proper offset formulas, and digital storage covers both decimal (KB, MB, GB) and binary (KiB, MiB, GiB) units.
Can I convert in reverse?
Yes, two ways: type directly in the To field and the From value recalculates automatically, or press the swap button to flip the units and carry the current result across.
Which unit categories are supported?
Eight: length, weight and mass, temperature, area, volume, speed, digital storage and time — over 60 units in total, from nautical miles to tebibytes.
Published · Last updated .
