Unit Converter
Exact conversions between metric, US customary and imperial units.
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How this is calculated
Each value is converted to one base unit per category (metre, kilogram, litre, square metre and so on) and then to the target unit. The factors are the legal definitions, so results are exact to the limits of the computer's arithmetic, about 15 significant digits. Results are shown to 10 significant digits.
- Inch, foot, yard, mile and pound: the 1959 international agreement (1 in = 2.54 cm, 1 lb = 0.45359237 kg).
- US gallon = 231 cubic inches = 3.785411784 L; cups, pints and quarts follow from it. Imperial gallon = 4.54609 L.
- Kilobyte, megabyte and so on use powers of 1,000; kibibyte, mebibyte and so on use powers of 1,024 (IEC prefixes).
- Calorie is the thermochemical calorie, 4.184 J. A food Calorie is a kilocalorie.
- Millimetres and inches of mercury are conventional values (marked "conventional" when you use them).
- Fuel economy is an inverse relation: litres per 100 km = 100 ÷ kilometres per litre.