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How to use the unit converter
- Choose a category: length, weight, volume, speed or temperature.
- Enter the value and pick the unit you have in From.
- Pick the unit you want in To. The result updates as you type.
Use Swap units to reverse the conversion, for example from kilometers back to miles.
How the conversion works
Each unit is compared with a base unit in its category: meters for length, kilograms for weight, liters for volume and meters per second for speed. To convert, multiply the value by the factor of the starting unit and divide by the factor of the target unit.
Example: 10 miles to kilometers. One mile is 1,609.344 meters and one kilometer is 1,000 meters, so 10 × 1,609.344 ÷ 1,000 = 16.09344 km.
Temperature works differently because the scales start at different zero points. The converter goes through Celsius. Fahrenheit becomes Celsius by subtracting 32 and multiplying by 5/9, and Kelvin is Celsius plus 273.15.
Common conversions
| From | To | Exact value |
|---|---|---|
| 1 inch | centimeters | 2.54 cm |
| 1 pound | kilograms | 0.45359237 kg |
| 1 US gallon | liters | 3.785411784 L |
| 1 knot | km/h | 1.852 km/h |
| 0 °C | °F | 32 °F |
Questions about unit conversion
Are the results exact?
The converter uses exact definitions for each unit, so the only rounding happens in the display, which shows up to four decimal places.
What is the difference between US and UK pints?
A US liquid pint is 16 US fluid ounces, about 473 ml. A UK (imperial) pint is 20 imperial fluid ounces, about 568 ml. Recipes often mean one or the other, so check which one a recipe uses.
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32. For example, 20 °C × 9/5 + 32 = 68 °F.