Converters
Convert length, weight, temperature, volume, area, speed, pressure, time and digital storage units.
13 tools · all free, all run in your browser
Area Converter
Convert area between square metres, square feet, acres, hectares and square miles for land and floor plans.
Open toolCooking Measurement Converter
Convert cups, tablespoons and teaspoons to grams and back, using real ingredient densities.
Open toolCurrency Converter
Convert between major world currencies using real, daily-updated European Central Bank exchange rates.
Open toolData Storage Converter
Convert digital storage between bits, bytes, kilobytes, megabytes, gigabytes, terabytes and petabytes.
Open toolEnergy Converter
Convert energy between joules, calories, kilocalories, watt hours, kilowatt hours, BTU and electronvolts.
Open toolLength Converter
Convert length and distance between metric and imperial units such as metres, feet, miles and inches.
Open toolPressure Converter
Convert pressure between pascals, kilopascals, bar, psi, atmospheres, torr and millimetres of mercury.
Open toolShoe Size Converter
Convert shoe sizes between US, UK, EU and centimetres, for men's and women's sizing.
Open toolSpeed Converter
Convert speed between km/h, mph, metres per second, feet per second, knots and Mach.
Open toolTemperature Converter
Convert temperatures between Celsius, Fahrenheit, Kelvin and Rankine with the exact formula shown.
Open toolTime Converter
Convert time between milliseconds, seconds, minutes, hours, days, weeks, months and years.
Open toolVolume Converter
Convert volume between litres, millilitres, cubic metres and US cooking units like cups, pints and gallons.
Open toolWeight Converter
Convert weight and mass between grams, kilograms, pounds, ounces, stones and tons instantly.
Open toolUnit conversion is the kind of task where a small slip becomes an expensive mistake, so each converter here shows not just the single answer you asked for but the same quantity expressed in every unit it supports. That makes it easy to sanity-check a result at a glance and to spot when you have picked the wrong unit — a US gallon rather than an imperial one, or a short ton rather than a tonne. Conversions are exact wherever the underlying definitions are exact.
Why exact definitions matter
Most everyday units are now defined exactly in terms of SI base units. An inch is exactly 25.4 millimetres, a pound is exactly 0.45359237 kilograms, and since the 2019 redefinition the kilogram itself is fixed by the Planck constant rather than by a metal cylinder in Paris. Because those relationships are exact rather than measured, conversions between them introduce no error beyond the rounding you choose to display.
The units that trip people up
Several unit names are shared by different quantities. A US liquid gallon is about 3.785 litres while an imperial gallon is about 4.546 — a 20% difference. A US short ton is 2,000 pounds, a UK long ton 2,240, and a metric tonne 1,000 kilograms. Fluid ounces differ between the two systems too. Temperature is different again: Celsius and Fahrenheit have both a different scale and a different zero point, which is why they need an offset as well as a ratio and why they cross at exactly -40 degrees.
Digital storage and its two conventions
Storage is the one place where the same prefix genuinely means two different numbers. Historically a kilobyte meant 1,024 bytes, following powers of two, and operating systems still report file sizes that way. Drive manufacturers use the strict SI meaning of 1,000 bytes, which is why a drive sold as 1 TB shows as roughly 931 GB in your file manager. The IEC introduced kibibyte, mebibyte and gibibyte to disambiguate, though the older usage remains widespread.