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Unit Converter

Convert length, mass, temperature, area, volume, speed, data and time. Exact, instant and entirely in your browser.

3 min read

What this tool does

Type a number, pick what it is now and what you want it in, and the answer appears. Everything is defined against one base unit per kind of measurement, so a conversion is exact rather than a chain of rounded steps. Temperature is handled on its own terms, because those scales have offsets as well as different sizes: zero degrees Celsius is not zero Fahrenheit, and a converter that treats it like every other unit gets it wrong everywhere. Data sizes keep the decimal and binary families separate, so a kilobyte is 1000 bytes and a kibibyte is 1024, which is the difference behind a drive sold as 500 GB showing up as 465. If you ask for something that cannot be converted, like metres into kilograms, it says so instead of inventing a number.

What you can use it for

  • Convert a recipe from cups and ounces into millilitres and grams.
  • Turn a distance from miles into kilometres, or the other way around.
  • Read a temperature quoted in Fahrenheit when you think in Celsius.
  • Work out why a drive sold as 500 GB shows up as 465 in your file manager.

How to use it

  1. Enter the number you want to convert.
  2. Pick the unit it is currently in.
  3. Pick the unit you want it in.
  4. Copy the result, which carries its unit symbol.

Everything runs inside your browser. No file is uploaded to any server. See more tools in this field.

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Frequently asked questions

What is the difference between a kilobyte and a kibibyte?

A kilobyte is 1000 bytes and a kibibyte is 1024. Both are listed here as separate units rather than being merged, because conflating them is exactly what makes a drive sold as 500 GB appear as 465 GB: the manufacturer counted in decimal and the operating system displayed in binary. The same gap applies at every step, and it grows as the numbers get bigger.

Why can I not convert metres into kilograms?

Because they measure different things and there is no answer to give. Rather than hiding the option, the tool lets you try and then tells you plainly, which is more useful than a dropdown that silently refuses to offer it.

Why is temperature handled differently?

Because those scales have a starting point as well as a size. Every other unit here can be converted by multiplying, since zero means zero in both units. Temperature does not work that way: zero Celsius is 32 Fahrenheit. Multiplying by a factor would be wrong at every value except by coincidence, so temperature is converted through Celsius with the proper offsets.

How precise are the results?

Conversions use the exact defined ratios, so an inch is exactly 0.0254 metres and a pound is exactly 453.59237 grams rather than a rounded approximation. Results are shown to ten significant digits, and very large or very small numbers switch to scientific notation instead of filling the screen with zeros.