Unit converter
Pick a category, enter a value and choose the units. You get the converted number and a note of how it was calculated.
How the unit converter works
Most conversions work in two moves: change your value into one standard unit (metres, kilograms, litres), then change it from that standard unit into the one you want. Doing it this way means the calculator only needs one number per unit, and it avoids the rounding that creeps in when you chain several conversions together.
Temperature is different because the scales do not share a zero point, so it uses its own formulas rather than a simple multiplier.
The formula behind it
- 1 mile = 1.609344 km
- 1 pound = 0.45359237 kg
- °F = °C × 9/5 + 32
- 1 US gallon = 3.785411784 litres
A worked example
Convert 5 km to miles: 5 × 1000 = 5,000 m, and 5,000 ÷ 1,609.344 = 3.1069 miles. And 100°C is 212°F, the boiling point of water.
Questions people ask
Are US and UK gallons the same?
No. A UK (imperial) gallon is about 4.546 litres, bigger than a US gallon at 3.785 litres. This calculator uses US gallons, quarts and cups, and UK pints.
Why is a nautical mile different?
It is tied to the curve of the Earth (one minute of latitude). Knots measure nautical miles per hour.
How accurate is it?
It uses the exact international definitions for each unit and rounds only the number shown.
Is 0 K possible?
0 kelvin is absolute zero. Nothing can be colder, so lower values are rejected.