Unit Converter
Twenty categories, hundreds of units — length, mass, temperature, area, volume, speed, time, data, pressure, energy, power, and more. Pick a category, type a value, and see it in every other unit at once.
What's covered
This converter spans twenty categories: length, mass, temperature, area, volume, speed, time, digital storage, pressure, energy, power, angle, frequency, data transfer rate, fuel economy, force, density, torque, illuminance, and acceleration. Within each, both metric and imperial/US units are included, alongside the scientific and niche ones — light-years and parsecs under length, electronvolts and BTUs under energy, knots and Mach under speed, carats and grains under mass. The "All units" panel converts your value into every unit in the category simultaneously, which is usually faster than picking a single target.
The conversions that aren't simple ratios
Most conversions are a single multiplication by a fixed factor, but a few are not, and this tool handles them correctly. Temperature is affine, not proportional: Celsius, Fahrenheit, Kelvin, and Rankine each have a different zero point, so converting needs an offset as well as a scale (0°C = 32°F = 273.15K, not a simple multiple). Fuel economy mixes two opposite kinds of measure — distance-per-fuel (mpg, km/L, where bigger is better) and fuel-per-distance (L/100km, where smaller is better) — so converting between them is an inverse relationship, not a ratio.
Decimal versus binary storage
Digital storage is a common source of confusion, so both conventions are included. The decimal units — KB, MB, GB, TB — use powers of 1000, the way drive manufacturers and networks label capacity. The binary units — KiB, MiB, GiB, TiB — use powers of 1024, the way operating systems actually count memory. This is why a "1 TB" drive shows up as roughly 931 GiB in your file manager: same bytes, different yardstick. The converter lets you move between the two precisely.
One thing it won't do
There's no currency converter here, and deliberately so. Exchange rates change by the second and can only come from a live feed, which would break the promise that this tool works entirely offline with nothing sent anywhere. For money, use a source with real-time rates. For everything with a fixed, physical relationship, this is built to be the only converter you need to bookmark.
Privacy
All conversions run in your browser. Nothing you enter leaves your device.