Unit Converter

Convert between metric and US customary units across eight categories: length, weight, temperature, volume, area, speed, time and digital data. Each conversion also shows the value in every other unit of that type.

What this unit converter does

• Length: metres, kilometres, centimetres, millimetres, miles, yards, feet, inches and nautical miles.
• Weight: kilograms, grams, milligrams, metric tons, pounds, ounces, stone and US tons.
• Temperature: Celsius, Fahrenheit and Kelvin.
• Volume: litres, millilitres, US gallons, quarts, pints, cups, fluid ounces, tablespoons, teaspoons, cubic metres and cubic feet.
• Area, Speed, Time and Data: square units, acres and hectares; m/s, km/h, mph, ft/s and knots; seconds to years; and bits to petabytes.

How it works

Each unit has a factor relative to a base unit. The calculator converts your value to the base unit and then to the unit you chose. The factors use the exact international definitions, including 1 inch = 2.54 cm, 1 yard = 0.9144 m, 1 pound = 0.45359237 kg and 1 nautical mile = 1,852 m. Temperature uses °F = °C × 9/5 + 32 and K = °C + 273.15.

Worked examples: 1 mile = 1.609344 km. 100°C = 212°F. 1 acre = 43,560 square feet. 60 mph = 96.56064 km/h. 0 K = −273.15°C.

Data units: 1,024 or 1,000?

In this converter a kilobyte is 1,024 bytes, a megabyte is 1,024 kilobytes, and so on, which is how many operating systems report file sizes. Strictly, 1,024-based units are called kibibytes (KiB), mebibytes (MiB) and so on, while SI prefixes mean powers of 1,000 (NIST: prefixes for binary multiples). Storage manufacturers usually use powers of 1,000, which is why a drive can look smaller in your operating system than on its box.

Things to keep in mind

Volume units here are US units (US gallon, US cup, US fluid ounce), which differ from imperial ones, and the ton is the US short ton. A month is 30 days and a year is 365 days. For professional, medical or engineering work, check results against your own standards.

Frequently asked questions

Is a US gallon the same as a UK gallon?
No. This converter uses the US gallon, which is smaller than the UK imperial gallon.

Why does the data converter say 1 GB is 1,024 MB?
It uses 1,024-based units. See the section above for how this differs from 1,000-based units.

Looking for more? See all our free academic and scientific calculators.