Unit Converter is a free tool that converts length, weight, temperature, area, volume, speed, data, pressure, energy and angle in one place. Pick a kind of measurement, type an amount and choose the two units; the answer appears as you type, along with the same value in every other unit. Everything is calculated in your browser and nothing is uploaded.
How to convert a unit
- Choose the kind of measurement at the top, such as Length or Temperature.
- Type the amount into Amount and pick the unit it is in under From.
- Choose the unit you want under To; the result updates instantly.
- Check the table below for the same amount in every unit of that kind, or press Swap to reverse the pair.
Worked examples
A 10 km run is 6.2137 miles, because one mile is exactly 1,609.344 metres. A 70 kg person weighs 154.32 pounds at 0.45359237 kg per pound. A 180 °C oven is 356 °F, and an American recipe calling for 1 cup needs 236.6 millilitres. Each of those is one multiplication against an exact factor — no lookup table with rounded values.
Metric, imperial and the three size traps
Most conversion mistakes come from three places. Gallons: the US one is 3.785 litres and the UK one is 4.546, a 20% difference that ruins fuel and recipe maths. Ounces: a fluid ounce measures volume while an ounce measures weight, so they cannot be converted into each other. Data: hard drives count 1 GB as 1,000,000,000 bytes but operating systems have long displayed 1,073,741,824, so a “500 GB” drive reads as about 465 GiB. This converter lists both decimal and binary data units by name to keep them apart.
Why temperature is the odd one out
Length and weight start at zero, so a single factor converts them. Temperature has an offset: 0 °C is 32 °F, not 0 °F. The calculator converts through Celsius, which also makes the −40 crossover come out right (−40 °C equals −40 °F). For dates and durations rather than measures, use theDate Difference Calculator.
Frequently asked questions
Are the conversion factors exact?
Yes. Where an exact international definition exists it is used — an inch is exactly 0.0254 metres and a pound exactly 0.45359237 kilograms — so rounding comes only from the display, never from the maths.
What is the difference between MB and MiB?
A megabyte (MB) is 1,000,000 bytes and a mebibyte (MiB) is 1,048,576 bytes, which is 1024 kibibytes. Hard-drive makers use the decimal units; operating systems have historically shown the binary ones, which is why a “500 GB” drive shows as about 465 GiB.
Which gallon and cup does this use?
The US liquid gallon (3.785 L) and US customary cups, tablespoons and teaspoons, because those are what most recipes and fuel figures mean. The UK gallon is included separately at 4.546 L.
Why is temperature different from the other conversions?
Length and weight scale from zero, so one value multiplies directly into another. Temperature has an offset, so the tool converts through Celsius — which is why 0 °C is 32 °F rather than 0 °F.
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