Unit Converter
Convert length, weight, temperature, volume, area and speed between metric and imperial units.
How your conversion is worked out
Every unit is turned into one base unit first, then into the unit you want.
- 1
Pick the units
100 cm →
inches - 2
Into metres
100 × 0.01 =
1 m - 3
Out to inches
1 ÷ 0.0254 =
39.37008 in - 4
The shortcut
1 cm =
0.393701 in
Read more: common conversion factors and temperature formulas
| From | To | Multiply by |
|---|---|---|
| Inches | Centimetres | 2.54 (exact) |
| Feet | Metres | 0.3048 (exact) |
| Miles | Kilometres | 1.609344 (exact) |
| Pounds | Kilograms | 0.45359237 (exact) |
| US gallons | Litres | 3.785411784 |
| Acres | Square metres | 4,046.86 |
| Knots | Kilometres per hour | 1.852 (exact) |
The formula
new value = value × factor
(temperature uses the formulas below)
Worked example
A 10 km run in miles: 10 ÷ 1.609344 = 6.21 miles. Someone 6 ft tall is 6 × 0.3048 = 1.83 m. A 30 °C day is 30 × 9 ÷ 5 + 32 = 86 °F.
Temperature
°F = °C × 9 ÷ 5 + 32
°C = (°F − 32) × 5 ÷ 9
K = °C + 273.15
A quick way to estimate: double the Celsius figure and add 30. 20 °C is about 70 °F (exactly 68 °F).
US or UK?
US and UK (imperial) gallons, pints and fluid ounces are different sizes. A UK gallon is about 20% bigger than a US gallon. Cups and spoons here are US measures, which most online recipes use.