One unit converter for every kind of measurement
This unit converter puts fourteen kinds of measurement behind one set of controls: length, weight, temperature, area, volume, speed, time, data storage, pressure, energy, power, fuel economy, angle and frequency — more than 200 units in all. Pick what you are measuring, type a number, and choose the units you have and want. The answer appears as you type, along with the formula and the same value in every other unit of that kind.
It is built for everyday moments: a recipe from the US, a car brochure from Europe, a plot of land measured in guntha, or a drive that shows less space than the box promised. Every factor comes from an official definition, and results are rounded cleanly instead of showing floating-point noise such as 0.30000000000000004.
How to use the Unit Converter
- Choose what you are measuring with the buttons at the top — Length, Weight, Temperature, Area, Volume, Speed, Time, Data, Pressure, Energy, Power, Fuel economy, Angle or Frequency.
- Type a number in the Value box. Decimals, fractions such as 3/4 and scientific notation such as 6.02e23 all work.
- Open From and To to pick the units; type a name or symbol in the search box to find one quickly. The round button between them swaps the direction.
- Read the result, the sentence underneath and the formula. Choose a Precision from 4 to 15 significant digits and press Copy to use the number elsewhere.
- Scroll down for the value in every unit of the chosen kind, tap any row to make it the target, or tap a common conversion to fill everything in at once.
Unit Converter features
Fourteen converters in one
Switch between measurement types without leaving the page; each remembers the units you used last.
Searchable, grouped unit lists
Units are grouped as metric, imperial or US customary and specialist, and you can search by name, symbol or nickname.
Exact definitions
International inch, pound and gallon definitions, exact SI constants and clearly labelled reference values such as Mach 1.
Clean numbers
Significant-digit rounding removes binary rounding noise, and very large or small values switch to scientific notation.
Formula for every pair
Linear, offset (temperature) and reciprocal (fuel economy) conversions each show the right formula.
Private and quick
Everything runs in your browser; nothing you type is sent anywhere.
Metric vs imperial: a quick guide
The metric system, formalised today as the International System of Units (SI), builds every unit from seven base units — the metre, kilogram, second, ampere, kelvin, mole and candela — and scales them with decimal prefixes. Moving from millimetres to kilometres or from grams to tonnes is just a matter of shifting the decimal point. Since 2019 all seven base units have been defined by fixed constants of nature, such as the speed of light and the Planck constant.
The imperial system grew out of older English units and was standardised in Britain in 1824. The United States inherited the earlier English units and kept them as US customary units. Most lengths and weights match between the two, but volumes do not: a US gallon is 3.785 L while an imperial gallon is 4.546 L, and a US pint is 16 fluid ounces while a UK pint is 20. Since 1959 both systems have been defined in metric terms — one inch is exactly 2.54 cm and one pound exactly 0.45359237 kg — so conversions between them can be exact.
In daily life the picture is mixed. The US uses customary units for almost everything outside science and medicine. The UK is metric for most trade but keeps miles on road signs, pints for beer and milk, and stones for body weight. India is officially metric, yet heights are often given in feet and inches, screens in inches, and land in local units that vary by state.
Metric prefixes
The same prefixes work with every metric unit, from metres and grams to watts, joules, bytes and hertz.
| Prefix | Symbol | Multiplier | Example |
|---|---|---|---|
| nano | n | 0.000000001 (10⁻⁹) | nanometre, nanosecond |
| micro | µ | 0.000001 (10⁻⁶) | micrometre, microgram |
| milli | m | 0.001 | millimetre, millilitre |
| centi | c | 0.01 | centimetre |
| kilo | k | 1,000 | kilogram, kilowatt |
| mega | M | 1,000,000 | megawatt, megahertz |
| giga | G | 1,000,000,000 | gigabyte, gigajoule |
| tera | T | 10¹² | terabyte, terahertz |
Dedicated converters for each measurement
Each type also has its own page with exact factor tables, worked examples and answers to common questions:
- Length converter — mm, cm, inches, feet, metres, miles, nautical miles and light-years.
- Weight converter — kg, lbs, ounces, stone, tonnes, carats, troy ounces and tola.
- Temperature converter — Celsius, Fahrenheit, Kelvin, Rankine and Réaumur.
- Area converter — sq ft, m², acres, hectares and Indian land units such as guntha and bigha.
- Volume converter — litres, US and UK gallons, pints, cups and cubic feet.
- Speed converter — km/h, mph, knots, m/s and Mach.
- Time converter — nanoseconds to centuries.
- Data storage converter — KB, MB, GB, TB and binary KiB, MiB, GiB.
- Pressure converter — psi, bar, kPa, atm and mmHg.
- Energy converter — joules, kWh, calories and BTU.
- Power converter — watts, horsepower, BTU/h and AC tonnage.
- Fuel economy converter — mpg, L/100 km and km/L.
- Angle converter — degrees, radians, gradians and DMS coordinates.
- Frequency converter — Hz, MHz, GHz, rpm and rad/s, with period and wavelength.
- Cooking converter — cups to grams by ingredient, spoons and oven temperatures.
- Shoe size converter — US, UK, EU, India and Japan sizes for men, women and kids.
- Height converter — feet and inches to cm and back, with a height chart.
Unit Converter FAQ
What can this unit converter convert?
Fourteen kinds of measurement: length, weight (mass), temperature, area, volume, speed, time, data storage, pressure, energy, power, fuel economy, angle and frequency, with more than 200 units between them.
How accurate is the unit converter?
Conversions use exact legal and scientific definitions wherever they exist, with double-precision arithmetic. You can display up to 15 significant digits; the answer is only as precise as the value you enter.
What is the difference between imperial and US customary units?
They share most length and weight units, but volumes differ. The imperial gallon is 4.54609 L and the US gallon is 3.785411784 L, and a UK pint has 20 fluid ounces against 16 in a US pint.
Which countries use the metric system?
Nearly every country uses metric units for official and most commercial purposes. The United States is the main exception in everyday life, and the UK still uses some imperial units, such as miles and pints.
Why does the result say 2.54 and not 2.5399999?
Binary arithmetic leaves tiny rounding errors in decimals. The converter rounds to the significant digits you choose, so you see the clean figure.
Is anything I type stored or sent anywhere?
No. All calculations run in your browser, and nothing you type is uploaded. Your last-used units are remembered only in your own browser storage.