Unit Converter (Length, Mass, Volume, Temperature & More)

Use this free unit converter to switch any measurement between metric and customary units. Pick a category — length, mass, volume, temperature, time, area or speed — choose your from and to units, and you’ll get the converted value plus the exact factor (or temperature formula) used.

How to use the unit converter

1. Choose a measurement category.
2. Pick the unit you are converting from and the unit you want to.
3. Type your value and read the result, the factor used, and the same amount in a few other common units.

How unit conversion works

Most conversions multiply by a fixed factor: every unit is defined relative to a base unit (for length the base is the meter), so converting means value × (from-factor / to-factor). Temperature is the exception — °C, °F and K are related by formulas, not a single factor.

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Frequently asked questions

How do you convert miles to kilometers?

Multiply miles by 1.609344. The converter does this for you and shows the factor, so 5 miles = 8.04672 km.

How is temperature converted?

Temperature uses formulas, not a factor: °F = °C × 9/5 + 32, and K = °C + 273.15. The tool applies the right formula automatically.

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Which units are supported?

Length, mass/weight, volume, temperature, time, area and speed — with the most common metric and US customary units in each category.

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Read the full lesson: learn the method step by step.

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