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Unit Converter
Convert between metric, imperial and US units for everyday measurements. Type on either side and the other updates instantly.
Converter
1 cm in every length unit
Select a row to make it the “To” unit. Results show up to 10 significant figures.
Common conversions
| 1 inch | 2.54 cm |
|---|---|
| 1 foot | 30.48 cm |
| 1 mile | 1.609344 km |
| 1 pound | 0.45359237 kg |
| 1 stone | 14 lb (6.35 kg) |
| 1 US gallon | 3.785411784 L |
| 1 UK gallon | 4.54609 L |
| 1 acre | 43,560 ft² (≈ 4,047 m²) |
| 0 °C | 32 °F |
| 100 °C | 212 °F |
| 1 kcal | 4.184 kJ |
| 1 atm | 101,325 Pa (≈ 14.7 psi) |
Metric, imperial and US customary
Most of the world uses the metric system. The US uses US customary units, and the UK mixes metric with imperial units — miles on road signs, pints in pubs, stones for body weight. Imperial and US units share names but not always sizes: inches, feet, miles and pounds are identical, while gallons, pints and fluid ounces differ.
Frequently asked questions
How do I convert Celsius to Fahrenheit?+
Multiply by 9/5 (1.8) and add 32. For example, 20 °C × 1.8 + 32 = 68 °F. To go back, subtract 32 and multiply by 5/9: 68 °F is (68 − 32) × 5/9 = 20 °C.
How many centimetres are in an inch?+
Exactly 2.54. The inch has been defined as 25.4 mm since 1959, so 12 inches (a foot) is 30.48 cm.
Why are there US and UK gallons and pints?+
They come from different historical standards. A US gallon is 3.785 litres and a UK (imperial) gallon is 4.546 litres, about 20% larger. The same applies to pints and fluid ounces, so check which one a recipe or fuel figure uses.
Why does my 1 TB drive show as 931 GB?+
Drive makers use decimal units (1 TB = 1,000,000,000,000 bytes), but Windows reports sizes in binary units of 1,024. 1012 bytes ÷ 1,024³ is about 931 GiB, which Windows labels “GB”.
How do I convert L/100 km to mpg?+
Divide 235.215 by the L/100 km figure for US mpg, or 282.481 for UK mpg. 8 L/100 km is about 29.4 mpg (US) or 35.3 mpg (UK). Because one is fuel per distance and the other distance per fuel, a lower L/100 km is better but a higher mpg is better.
How accurate are the conversions?+
They use the exact legal definitions where one exists, such as 1 lb = 0.45359237 kg, and show up to 10 significant figures. Very large or small results are shown in scientific notation.
Is anything I type stored or sent anywhere?+
No. Conversions run in your browser and nothing is saved or uploaded.