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This unit converter switches between metric and imperial units for length, weight, temperature and volume. Convert centimetres to inches, kilograms to pounds, Celsius to Fahrenheit, litres to gallons and much more.
Pick a category, enter a value, then choose the units to convert from and to. The result updates instantly with up to six decimals of precision.
The factors between metric and imperial units are fixed by international definition — they are exact, not rounded approximations. These are the ones this converter uses:
| 1 inch | 2.54 cm |
| 1 foot | 0.3048 m |
| 1 yard | 0.9144 m |
| 1 mile | 1.609344 km |
| 1 ounce (oz) | 28.349523125 g |
| 1 pound (lb) | 0.45359237 kg |
| 1 stone | 6.35029318 kg |
| 1 US gallon | 3.785411784 L |
| 1 UK (imperial) gallon | 4.54609 L |
| 1 US fluid ounce | 29.5735295625 mL |
| °C to °F | °C × 9/5 + 32 |
| °F to °C | (°F − 32) × 5/9 |
| °C to Kelvin | °C + 273.15 |
Values are exact by definition. Source: NIST Special Publication 811 (Guide for the Use of the International System of Units).
Metric scales by tens — 10 mm to a centimetre, 1000 metres to a kilometre — so conversions within the system are easy. Imperial units (inch, foot, mile, pound, gallon) come from older standards, so crossing between systems needs a fixed factor, which is exactly what this converter applies.
Recipes and road signs are the everyday reasons to convert. A US cup is about 237 ml, an oven at 180 °C is 356 °F, and 100 km/h is roughly 62 mph.
Some imperial units differ by country. A US gallon (3.785 L) is smaller than a UK gallon (4.546 L), and the pints differ too. The volume units here use US measures, so check which standard a recipe assumes.
Each unit is stored as a factor relative to a base unit, so the value is converted to the base and then to the target — that keeps results consistent in both directions. Temperature is different because the scales do not share a zero: Celsius to Fahrenheit is °C × 9/5 + 32, and Celsius to Kelvin is °C + 273.15. Definitions follow the international system of units (SI).
Length, weight, temperature, volume and speed — between metric and imperial systems.
Multiply by 9/5 and add 32. 20°C equals 68°F.
One mile is about 1.609 km, and one kilometre is about 0.621 miles.