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Unit Converter

Convert between metric, US customary and imperial units in ten categories, with a table of every unit.

Runs locally in your browser – your data is not uploaded

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About the Unit Converter

This unit converter covers ten everyday categories: length, mass and weight, temperature, area, volume, speed, time, digital storage, pressure and energy. Enter a value, choose the unit to convert from and to, and the result appears immediately, together with a table that converts the value into every unit of the category.

Conversion factors use the exact legal definitions wherever they exist: an inch is exactly 0.0254 m, a pound exactly 0.45359237 kg, a US gallon exactly 3.785411784 L and an imperial gallon exactly 4.54609 L. US customary and imperial (UK) units that share a name – gallons, pints, fluid ounces – are listed separately and clearly labelled.

Everything is calculated in your browser. Results are rounded to 12 significant digits, which is more than enough for cooking, travel, school work and most technical tasks, and are for general information.

How to use it

  1. Choose a category such as Length, Temperature or Volume.
  2. Type the value in the Value field. Use a dot for decimals; thousands separators (1,000) and scientific notation (1e-6) are accepted.
  3. Select the From and To units. The Swap button exchanges them.
  4. Read the result and use Copy to copy the number. The table below lists the value in every unit of the category.
  5. Use Reset to go back to 1 and the default units of the category.

Features

  • Exact definitions: Factors come from the international definitions of the inch, foot, yard, mile (1609.344 m), nautical mile (1852 m), pound, US and imperial gallon, and the thermochemical calorie (4.184 J).
  • US customary vs imperial: US cups, tablespoons, teaspoons, fluid ounces, pints, quarts and gallons are separate from their imperial (UK) counterparts, and metric cups and spoons (250, 15 and 5 mL) are included for recipes.
  • Decimal and binary storage units: kB, MB, GB and TB are powers of 1000; KiB, MiB, GiB and TiB are powers of 1024. Bits and bytes are both available, for example to compare a 100 Mbit/s connection with file sizes.
  • All temperature scales: Celsius, Fahrenheit, kelvin and Rankine, with the conversion formula shown and a warning for values below absolute zero.
  • Clean numbers: No floating-point noise such as 0.30000000000000004: results are rounded to 12 significant digits, and very large or small values use scientific notation.
  • Conversion table: See the value in every unit of the category at once, which makes it easy to pick the most convenient unit.

Examples

Cooking

A US recipe asks for 2 cups of milk. Converting 2 US cups to millilitres gives 473.176473 mL. A UK pint is 568.26125 mL, while a US pint is 473.176473 mL.

Weather and fever

30 °C is 86 °F, and a body temperature of 98.6 °F is exactly 37 °C.

Disk sizes

A drive sold as 1 TB holds 1,000,000,000,000 bytes, which the table shows as about 931.32 GiB – the number many operating systems display as "GB".

Tyre pressure

2.4 bar is about 34.81 psi, and 32 psi is about 2.21 bar.

Limitations and notes

  • Months and years in the Time category are averages of the Gregorian calendar (30.436875 and 365.2425 days). For calendar dates use the date difference calculator.
  • Cups and spoons are standard measures; real kitchen tools and some countries (for example Australia, where a tablespoon is 20 mL) differ.
  • The acre and mile are the international units; the slightly different US survey foot and survey mile are not included.
  • Mass and weight are treated as the same thing (kilograms and pounds), as in everyday use. Force units such as newtons are not included.
  • Results are rounded to 12 significant digits; the underlying arithmetic uses double-precision floating point numbers.

Frequently asked questions

How do I convert Celsius to Fahrenheit?

Multiply by 9/5 (1.8) and add 32: 20 °C × 1.8 + 32 = 68 °F. In the other direction subtract 32 and divide by 1.8. The converter shows the formula for the units you select.

What is the difference between a US gallon and an imperial gallon?

A US gallon is 3.785411784 litres (231 cubic inches); an imperial gallon, used in the UK, is 4.54609 litres, about 20% larger. Pints and fluid ounces differ too: a US pint has 16 US fluid ounces, an imperial pint 20 imperial fluid ounces.

Is 1 GB 1000 MB or 1024 MB?

Both conventions exist. In the SI (decimal) system 1 GB = 1000 MB = 1,000,000,000 bytes, which storage makers use. The binary units are called GiB and MiB: 1 GiB = 1024 MiB = 1,073,741,824 bytes. Some operating systems show binary values with the GB label.

How many grams are in an ounce?

An avoirdupois ounce, used for food and everyday weights, is exactly 28.349523125 g (1/16 of a pound). A troy ounce, used for precious metals, is 31.1034768 g.

Which calorie does the converter use?

The thermochemical calorie, 1 cal = 4.184 J. The "Calories" on food labels are kilocalories: 1 kcal = 4.184 kJ.

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