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Cuisdev

Unit Converter

Length, weight, temperature, area, volume and speed

  • Runs in your browser
  • No sign-up
  • Free forever
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How to use the Unit Converter

  1. 1

    Pick a category such as Length, Weight or Temperature, or type a unit in the search box (for example psi or cups) to jump straight to it.

  2. 2

    Type the value in the From box and choose its unit. Expressions work too, such as 5 ft 11 in or 1 h 30 min, and a decimal comma such as 1,5 is understood.

  3. 3

    Choose the unit to convert to. The result appears instantly, with the conversion rule written out underneath.

  4. 4

    Check the table on the right to see the same value in every unit of the category, and click a row to make it the target unit.

  5. 5

    Use Swap to reverse the conversion, Precision to round the result, and Copy link to share exactly this conversion.

Features

  • 14 categories, from length and weight to data storage, fuel economy and frequency
  • Exact legal definitions, such as 1 inch = 2.54 cm and 1 pound = 0.45359237 kg
  • Temperature conversions between Celsius, Fahrenheit, Kelvin and Rankine, with the formula in words
  • Mixed-unit expressions like 5 ft 11 in, 6'2" or 1 h 30 min
  • Search that finds any unit across all categories
  • The value in every unit of the category at once, each with a copy button
  • Adjustable precision and scientific notation for very large or small values
  • Shareable links that reopen the same conversion

One converter for everyday units

Recipes in cups, tyre pressures in psi, a weather forecast in Fahrenheit, a download quoted in megabits: unit conversion is a small task that comes up constantly. This converter covers fourteen categories in one place, accepts the way people actually write measurements, and shows the answer together with the rule behind it, so you can check the result or do it in your head next time.

Type the value the way you would say it. A height of 5 ft 11 in, a running time of 1 h 30 min, or a European-style 1,5 all work. The line under the input shows exactly how it was understood.

Common conversions

FromToRule
1 inch2.54 cmexact by definition
1 foot0.3048 mexact by definition
1 mile1.609344 kmexact by definition
1 pound0.45359237 kgexact by definition
1 US gallon3.785411784 Lexact by definition
0 °C32 °Fmultiply by 1.8, then add 32
100 km/h62.137 mphdivide by 1.609344

Precision and very large or small values

Results are calculated with full double precision. The Precision menu only changes how many significant digits are shown, from three for a quick estimate to fifteen for engineering work. Values beyond a trillion or below a millionth switch to scientific notation, such as 9.46 × 1015 metres in a light year, and the copy buttons copy the plain number so it pastes cleanly into a spreadsheet.

To convert numbers between binary, octal, decimal and hexadecimal, use the Number Base Converter. For dates and times rather than durations, the Timestamp Converter turns Unix timestamps into dates in any time zone.

Frequently asked questions

How exact are the conversions?
Imperial and US units use their exact legal definitions in metric terms: the international inch is exactly 2.54 cm, the pound exactly 0.45359237 kg, the US gallon exactly 3.785411784 litres and the imperial gallon exactly 4.54609 litres. Results are calculated in full double precision and only rounded for display, which you control with the Precision menu.
Why is 1 GB not 1024 MB here?
Gigabyte (GB) is an SI unit and means 1,000,000,000 bytes, which is how drive makers and network speeds count. The binary units are gibibyte (GiB), mebibyte (MiB) and so on, where each step is 1024. Operating systems often show GiB but label it GB, which is why a 1 TB drive appears as about 931 GB. Both families are in the Data category.
Why does converting fuel economy give such different numbers?
Litres per 100 km measures how much fuel a distance needs, while miles per gallon measures how far a fuel amount goes, so one is the reciprocal of the other. That is why doubling mpg does not halve the litres in a straight line. US and UK gallons also differ by about 20 percent, so a car rated 30 mpg in the US is about 36 mpg in UK units.
Can I type feet and inches together?
Yes. Type expressions such as 5 ft 11 in, 5'11" or 1 m 20 cm in the From box. The parts are added together and expressed in the From unit, and the line under the box shows how the input was read. Each number needs its own unit. Temperatures cannot be added this way because the scales do not start at zero.
Which month and year lengths are used for time?
A year is the average Gregorian year of 365.2425 days, and a month is one twelfth of that, 30.436875 days. Those averages are right for long spans and for rates such as salaries. For the exact number of days between two specific dates, use a date difference calculator instead.
Is my data sent anywhere?
No. Every conversion is calculated in your browser. The current conversion is stored in the page address so you can bookmark or share it, and your last settings are remembered on this device.

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