Unit Converters

Accurate unit converters built on exact international definitions – metric, imperial and US units side by side. Type a value, pick the units, and see every other unit in the category at once.

All-in-One Unit ConverterEvery unit type in one place – switch categories with a click.

Length ConverterMetres, centimetres, millimetres, kilometres, inches, feet, miles and more.

Area ConverterSquare metres, hectares, acres, square feet, km² and more.

Weight ConverterKilograms, grams, pounds, ounces, stones, tonnes, carats, tola.

Temperature ConverterCelsius, Fahrenheit, Kelvin and Rankine with formulas.

Volume ConverterLitres, millilitres, gallons (US & UK), cups, cubic metres, barrels.

Speed Converterkm/h, mph, m/s, knots and feet per second.

Time ConverterSeconds, minutes, hours, days, weeks, months, years.

Data Storage ConverterBytes, KB, MB, GB, TB and binary KiB, MiB, GiB.

Internet Speed ConverterMbps, Gbps, MB/s and more – plus what your speed really means.

Pressure ConverterBar, psi, kPa, atm, mmHg and more.

Energy ConverterJoules, calories, kWh, BTU, therms and more.

Power ConverterWatts, kilowatts, horsepower, BTU/h and tons of refrigeration.

Angle ConverterDegrees, radians, gradians, arcminutes and turns.

Fuel Economy ConverterL/100 km, km/L, US mpg and UK mpg.

Frequency ConverterHz, kHz, MHz, GHz, RPM and rad/s.

Force ConverterNewtons, kN, kilogram-force, pound-force and dynes.

Torque ConverterN·m, lbf·ft, lbf·in and kgf·m.

Number Base ConverterBinary, octal, decimal, hexadecimal and any base from 2 to 36.

Roman Numeral ConverterNumbers to Roman numerals and back (1–3999).

Time Zone ConverterConvert a time between any world time zones, with daylight saving.

Unit Converters: common questions

How accurate are the unit converters?

They use exact international definitions where they exist – for example 1 inch = 2.54 cm and 1 pound = 0.45359237 kg – and show up to 10 significant digits.

Can I share a specific conversion?

Yes. The page address updates as you convert (for example ?from=m&to=cm&v=5), so you can bookmark or share that exact conversion.

What is the difference between US and imperial units?

Some units share a name but differ in size. A US gallon is 3.785 L while an imperial (UK) gallon is 4.546 L. Both are listed separately.