Unit converter: length, mass, volume, temperature, area, speed, time, data size, pressure, energy, angle and fuel economy

Category
From
To
Precision

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In every unit

About the Unit Converter

This converter changes a number from one unit to another across twelve categories: length, mass, volume, temperature, area, speed, time, data size, pressure, energy, angle and fuel economy. Choose a category, type a value, pick the From and To units and the answer appears as you type.

Underneath the result, a table shows the same value in every unit of the category, each with its own copy button. The units you picked are highlighted. Conversion factors use the exact definitions wherever there is one, and temperature and fuel economy are handled with their own formulas rather than a simple multiplier.

Everything is calculated in your browser, so nothing is uploaded.

How to use it

  1. Pick a category from the tabs at the top.
  2. Type the value you want to convert.
  3. Choose the From unit and the To unit, or press the swap button to flip them.
  4. Set the precision if you need a fixed number of decimals, then press Copy, or copy any row of the table.

Frequently asked questions

How do I convert between units?

Pick a category, type the number, then choose the unit you are converting from and the unit you want. The result updates as you type. Press the swap button to flip the two units, and use the table underneath to see the same value in every other unit of that category.

How are Celsius, Fahrenheit and Kelvin converted?

Temperature scales have different zero points, so they are converted with an offset as well as a ratio. Fahrenheit is Celsius times 9/5 plus 32, and Kelvin is Celsius plus 273.15. That is why 0 °C is 32 °F and 273.15 K, and why -40 is the same on both Celsius and Fahrenheit. The tool tells you if a value is below absolute zero.

How accurate are the conversions?

The factors are the exact legal definitions where they exist: an inch is 25.4 mm, a pound is 0.45359237 kg, a US gallon is 3.785411784 liters and a mile is 1609.344 m. The maths uses standard double precision numbers, which hold about 15 digits. Pick Full in the precision menu to see 15 significant digits.

What does the precision setting do?

Auto shows 8 significant digits and drops trailing zeros, so 1 km is 0.62137119 mi. A number of decimals rounds every result to that many places, which suits prices and recipes. Full shows 15 significant digits. Very large and very small answers switch to scientific notation, for example 1.6e-19.

How do mpg and L/100 km convert?

They measure the same thing from opposite ends. Miles per gallon is distance per fuel, while liters per 100 km is fuel per distance, so one is the inverse of the other. 30 mpg (US) is about 7.84 L/100 km. US and imperial gallons differ in size, so the tool lists mpg (US) and mpg (UK) separately, and 30 mpg (US) is about 36 mpg (UK).

What is the difference between MB and MiB?

MB is a megabyte, 1,000,000 bytes, which is what storage makers and networks use. MiB is a mebibyte, 1,048,576 bytes (1024 squared), which is how many operating systems count memory. The same goes for KB and KiB, GB and GiB, and so on. Both are listed so you can pick the one you mean.

Which gallon, ton and pint does it use?

US and imperial versions are listed separately and labeled, because they are different sizes: a US gallon is 3.785 L and an imperial gallon is 4.546 L. For mass, ton means the US short ton of 2000 lb, imperial ton is the 2240 lb long ton and t is the metric ton of 1000 kg. Months are an average of 30.4375 days and a year is 365.25 days.

Is anything sent to a server?

No. Every conversion runs in your browser and nothing you type is uploaded. The category, units and value are kept in the page address so you can bookmark or share a conversion.