Unit Converter
Choose a category, then type in either box. Conversions are exact where the unit is defined exactly and run entirely on your device.
Converter
All units
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How the conversions work
Every unit is converted through one base unit per category (metres, kilograms, kelvin, cubic metres and so on) using the official definitions. Many are exact by law: 1 inch is exactly 25.4 mm, 1 pound is exactly 0.45359237 kg, 1 US gallon is exactly 231 cubic inches (3.785411784 L) and 1 imperial gallon is exactly 4.54609 L. Results are shown to 10 significant figures with trailing zeros removed.
Temperature scales have different zero points, so they use formulas rather than a single factor: °F = °C × 1.8 + 32 and K = °C + 273.15. Fuel economy is inverse: miles per gallon measures distance per fuel, while litres per 100 km measures fuel per distance, so L/100 km = 235.215 ÷ mpg (US) or 282.481 ÷ mpg (UK).
FAQ
Why does my 1 TB drive show as 931 GB?
Drive makers use decimal units (1 TB = 1,000,000,000,000 bytes) while many operating systems count in binary units (1 GiB = 1,073,741,824 bytes) but label them "GB". 1 TB is about 931.32 GiB. The Data category shows both kB/MB/GB (powers of 1000) and KiB/MiB/GiB (powers of 1024).
US or imperial cups, pints and gallons?
They differ. A US pint is 16 US fluid ounces (473 mL); an imperial pint is 20 imperial fluid ounces (568 mL). Recipes from the US use the US cup (about 237 mL), most others use the 250 mL metric cup. Choose the matching unit in the Volume or Cooking category.
Is anything sent to a server?
No. The conversion tables live in a WebAssembly module that runs in your browser. It works offline once loaded.