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Unit Converter

Convert length, mass, temperature, volume, data and eight more — with every unit of the category listed at once. Everything is calculated in your browser.

1 cm in every length unit

Click any row to copy its value.

About this unit converter

A free converter covering thirteen categories: length, mass, temperature, volume, area, speed, data, time, pressure, energy, power, angle and fuel economy. Type into either box and the other follows, and every unit of the category is listed underneath so you can see the whole picture rather than one answer at a time.

How it works

  1. 1
    Pick a category

    Length, mass, temperature and ten more. The category decides which units are offered, so you never see an impossible pair like centimetres to kilograms.

  2. 2
    Type in either box

    Conversion runs in both directions. Enter the value you know on whichever side you know it, and the other side updates as you type.

  3. 3
    Read the whole category

    Below the two boxes, the same value appears in every unit of the category at once - useful when you know the quantity but not yet which unit you want it in.

  4. 4
    Copy what you need

    Click any row to copy its value, or use the copy button beside the result.

Privacy

Every conversion is arithmetic done in your browser. There is no API call, no lookup service and no record of what you converted - the page works the same with the network switched off.

Working with dates rather than quantities? Try the Date Calculator.

Frequently asked questions

Are the conversion factors exact?
Where an exact value exists, yes. The 1959 international yard and pound agreement fixes the inch at exactly 25.4 mm and the pound at exactly 0.45359237 kg, so the imperial lengths and masses here are exact rather than rounded and they round-trip without drift. Where a unit is defined by convention rather than exactly - Mach, or an average calendar month - the page says so next to it.
Why does temperature behave differently from the other categories?
Because it has an offset as well as a scale. Zero Celsius is not zero Fahrenheit, so temperature cannot be a single multiplication the way metres to feet can. The converter treats it separately, which is why -40 °C correctly comes out as -40 °F.
What is the difference between MB and MiB?
A megabyte is 1,000,000 bytes and a mebibyte is 1,048,576. Drive manufacturers use the decimal one and operating systems often report the binary one, which is why a "500 GB" disk shows up as about 465 GiB. Both are listed here so you can see the gap rather than guess at it.
Why are miles per gallon and litres per 100 km not a simple factor?
They measure opposite things: one is distance per volume, the other volume per distance. More miles per gallon means fewer litres per 100 km, so converting between them is a reciprocal rather than a multiply. It also means zero litres per 100 km has no miles-per-gallon answer at all, and the tool says so rather than printing infinity.
Which gallon and which ton?
Both. US and UK gallons differ by about 20%, and a short ton, a long ton and a tonne are three different masses, so each is listed separately with its origin rather than collapsed into one ambiguous entry.

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