General
Unit converter.
Start with the popular 1 inch → 2.54 cm example, or choose any length, weight, volume, area, speed or temperature units. Nothing is sent anywhere.
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Metric and imperial quick reference
| Imperial / US unit | Metric equivalent |
|---|---|
| 1 inch | 2.54 cm (exact) |
| 1 foot | 0.3048 m (exact) |
| 1 yard | 0.9144 m (exact) |
| 1 mile | 1.609344 km (exact) |
| 1 pound | 0.45359237 kg (exact) |
| 1 ounce | 28.349523 g |
| 1 US gallon | 3.785412 L |
| 1 imperial gallon | 4.54609 L |
| 1 mile per hour | 1.609344 km/h (exact) |
Source: NIST SP 811, Appendix B: Conversion Factors, including B.9 (temperature, speed). Results are shown to at most 6 decimal places. For kitchen measures, see the cooking converter.
Unit conversion questions
How many centimetres are in an inch?
Exactly 2.54 cm. The inch is defined as 0.0254 metre, so 1 in = 2.54 cm and 1 ft = 30.48 cm.
How many kilograms are in a pound?
Exactly 0.45359237 kg, so 1 lb is about 0.4536 kg and 1 kg is about 2.2046 lb.
What is the difference between a US gallon and an imperial gallon?
A US gallon is 3.785412 litres. A Canadian or UK (imperial) gallon is 4.54609 litres, about 20% larger. Pick the right one when converting fuel or recipes.
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32: F = C x 9/5 + 32. To go back, subtract 32 and multiply by 5/9. Kelvin is Celsius + 273.15.
Where do the conversion factors come from?
From NIST Special Publication 811, Appendix B (Conversion Factors) and Appendix B.9 for temperature. Where NIST defines a factor exactly, this page uses the exact value; the rest are derived from those definitions.