Unit Converter
Convert between metric and imperial units instantly. Pick a category, type a value, and all conversions update live.
How to convert between metric and imperial units
Unit conversion is just multiplication by a fixed factor. To convert from one unit to another you multiply by the ratio between them — for example, because one inch is exactly 2.54 centimetres, you convert inches to centimetres by multiplying by 2.54, and centimetres to inches by dividing by 2.54. Temperature is the one exception: because the Celsius and Fahrenheit scales start at different points, you convert with a formula rather than a single factor.
The conversions people look up most
| From | To | Multiply by |
|---|---|---|
| Inches | Centimetres | 2.54 |
| Miles | Kilometres | 1.60934 |
| Kilograms | Pounds | 2.20462 |
| Stones | Kilograms | 6.35029 |
| Litres | UK pints | 1.75975 |
| Litres | US gallons | 0.264172 |
| Square metres | Square feet | 10.7639 |
| km/h | mph | 0.621371 |
Temperature: Celsius and Fahrenheit
To convert Celsius to Fahrenheit, multiply by 9/5 and add 32
(°F = °C × 9/5 + 32). To go the other way, subtract 32 and
multiply by 5/9 (°C = (°F − 32) × 5/9). The two scales read
the same at −40°, which is the only temperature that is identical in both.
Kelvin, used in science, is simply Celsius plus 273.15.
Frequently asked questions
Why is one inch exactly 2.54 cm?
Since 1959 the inch has been defined internationally as exactly 25.4 millimetres by agreement between the English-speaking countries, which makes inch-to-centimetre conversions exact rather than approximate.
What's the difference between UK and US gallons and pints?
They're different sizes. A UK (imperial) gallon is about 4.546 litres, while a US gallon is about 3.785 litres. A UK pint is 568 ml but a US pint is 473 ml — which is why a "pint" of beer differs on each side of the Atlantic. This converter lets you pick the correct one.
How do I convert my weight from stones to kilograms?
Multiply your weight in stones by 6.35029. So 12 stone is about 76.2 kg. If your weight is in stones and pounds, convert the pounds separately (1 lb = 0.453592 kg) and add them together.
Are these conversions exact?
Length, weight, area and volume factors are exact or accurate to six significant figures, which is far more precise than everyday use requires. Results are rounded for readability but calculated at full precision.