Unit Converter

A tool that expresses the same quantity in a different unit. The physical amount does not change — 1 foot and 30.48 centimeters are the same length, described two ways. This converter covers length, weight, temperature, area, volume, speed, time and digital storage, and everything it does runs in your browser.

Pick the category, choose the unit you are converting from, type the value, and choose the unit you want. The result updates as you type. There is no Convert button because there is nothing to wait for — the arithmetic is a multiplication, and it happens on every keystroke.

Through a conversion factor: a fixed number relating one unit to another. 1 inch is exactly 2.54 centimeters, so inches become centimeters by multiplying by 2.54 and centimeters become inches by dividing. This tool converts everything through a single base unit per category — into meters, then out to the target — which is why every unit needs one factor rather than one for every other unit it could pair with.

Divide by 2.54, since 1 inch is exactly 2.54 cm. So 100 cm is 39.37007874 inches, and 30 cm is about 11.81 inches. Going the other way, multiply inches by 2.54.

Multiply by 0.3048, which is exact — the international foot has been defined as exactly 0.3048 m since 1959. So 5 feet is 1.524 meters and 10 feet is 3.048 meters. To go from meters to feet, divide by 0.3048, or multiply by about 3.280839895.

Multiply by 1.609344, which is exact. So 10 miles is 16.09344 km and 26.2 miles — a marathon — is about 42.16 km. Kilometers to miles is the reverse: multiply by about 0.6213711922, so 100 km is roughly 62.14 miles.

Multiply by about 2.204622622. The exact relationship runs the other way — one pound is defined as exactly 0.45359237 kg — so kilograms to pounds is a division by that figure. 70 kg is about 154.32 lb, and 100 kg is about 220.46 lb.

Multiply by 9/5 and add 32: (°C × 9/5) + 32. So 0 °C is 32 °F, 37 °C is 98.6 °F, and 100 °C is 212 °F. The addition is what makes temperature different from every other category here — there is no single number you can multiply by, because the two scales do not share a zero.

Subtract 32, then multiply by 5/9: (°F − 32) × 5/9. So 100 °F is about 37.78 °C and 32 °F is 0 °C. A useful landmark: −40 is the one temperature where both scales give the same number.

It depends which gallon. For US gallons divide by 3.785411784, so 2 liters is about 0.53 US gallons. For imperial gallons divide by 4.54609, so 2 liters is about 0.44 imperial gallons. This converter lists both separately and labels each one, because the two differ by about 20% and sharing a name is exactly how that becomes a mistake.

Multiply by 0.09290304, which is 0.3048 squared. So 1,000 sq ft is about 92.9 m². Going the other way, one square meter is about 10.76391042 square feet. Area factors are always the square of the length factor, which is also why rounding the length factor first produces a noticeably wrong area.

Metric units scale by powers of ten — 1000 mm to the meter, 1000 m to the kilometer — so converting within the system is moving a decimal point. Imperial and US customary units grew from separate historical measures, so their relationships are irregular: 12 inches to a foot, 3 feet to a yard, 1760 yards to a mile. Both are equally precise; metric is simply easier to convert inside. Most countries use metric for official purposes, and imperial units remain in common everyday use in several, including for road distances and body weight.

They measure the same thing at different sizes: a kilogram is about 2.2 pounds. The kilogram is the SI base unit of mass; the pound is defined in terms of it, at exactly 0.45359237 kg. Strictly both are units of mass rather than weight, though in everyday use the words are interchangeable and the conversion is the same either way.

Both the size of a degree and the position of zero. A Celsius degree is 1.8 times the size of a Fahrenheit degree, and Celsius puts zero at the freezing point of water where Fahrenheit puts it at 32. That is why converting needs a formula and not a factor — and why the scales cross at exactly −40.

The SI base unit of temperature. Its degrees are the same size as Celsius degrees but its zero is absolute zero, the coldest anything can be, so 0 K is −273.15 °C. It is used in science and engineering because it has no negative values and ratios in it are meaningful. It is written without a degree sign: 300 K, not 300 °K.

A gigabyte (GB) is 1,000,000,000 bytes. A gibibyte (GiB) is 1,073,741,824 bytes — 1024³ rather than 1000³ — so a GiB is about 7.4% larger. Both are in this converter as separate units and neither borrows the other's name.

Both exist, and which one you are looking at depends on who wrote the label. Drive manufacturers use decimal units, so a 1 TB drive holds 1,000,000,000,000 bytes. Most operating systems report in binary units while still writing “GB”, so that drive shows as about 931 — which is the correct number of gibibytes, under the wrong name. This converter keeps the two families apart and uses the IEC names (KiB, MiB, GiB, TiB) for the binary ones.

Because your operating system is showing gibibytes and calling them GB. 1 TB is exactly 1,000,000,000,000 bytes, and dividing by 1024³ gives 931.32 — so the drive is the size it says, and the label on your screen is using the other family of units. Nothing is missing. Convert 1 TB to GiB here and you will get the same 931.

Yes. Negative values are ordinary in temperature and the converter handles them normally — −40 °C, −273 °C and anything between. The one limit is absolute zero: nothing is colder than −273.15 °C, so a value below that is rejected with an explanation rather than converted into a number that could not exist.

Yes. A negative length, weight or speed is perfectly valid as a difference or a direction — a −5 m elevation change, a −2 kg weight difference — so nothing outside temperature is constrained. The converter only refuses input it genuinely cannot interpret.

Yes, and very large and very small ones too. You can also type exponent notation like 1e6, paste a grouped figure like 1,609.344 straight from a spreadsheet, and use a leading decimal point like .5. Results beyond about 10¹⁵ or below 10⁻⁶ are shown in scientific notation, because a screen full of zeros is harder to read than 8 × 10¹².

It shouldn't — and if a converter shows you something like 3.0480000000000005, that is floating-point noise leaking onto the screen rather than a real figure. Computers store decimals in binary and most decimal fractions have no exact binary form, so tiny errors appear around the sixteenth significant digit. This converter keeps full precision through the arithmetic and rounds to ten significant digits only when displaying, which is far more precision than any physical measurement justifies and well clear of where the noise lives.

The factors are exact by international agreement wherever such a definition exists, and they are written out in full rather than rounded. The inch is exactly 2.54 cm and the pound exactly 0.45359237 kg, both fixed by the 1959 international yard and pound agreement; the nautical mile is exactly 1852 m; the US gallon is exactly 231 cubic inches; the acre is exactly 4840 square yards. Rounding a factor before using it is what introduces error, especially in area and volume where it gets squared or cubed.

As labelled averages, because they are not fixed durations. A month is 28 to 31 days and a year is 365 or 366, so the converter uses the mean Gregorian figures — 30.436875 days for a month and 365.2425 days for a year — and calls both units “average” wherever they appear. Everything from milliseconds to weeks is exact.

Both, listed separately. US and imperial measures share names but not sizes: a US gallon is 3.785411784 L and an imperial gallon is 4.54609 L, and the same split applies to pints and fluid ounces. Every one of them carries its system in its own name, so a result line reads “2 US gallons” rather than an ambiguous “2 gallons”.

It exchanges the two units and leaves your number where it is, so meters → feet becomes feet → meters with the same value. It deliberately does not move the result into the input: that would look similar but would quietly replace what you typed with a rounded figure, and pressing it twice would not bring you back.

Yes. The link button puts the category, both units and the value into the URL and copies it, so anyone opening the link sees exactly the conversion you were looking at. The figures travel in the link itself — nothing is stored on a server, and there is no identifier attached.

Yes. The layout stacks with the converter first and the result immediately below, the value field opens a numeric keypad, the unit pickers use your phone's native picker, and the tables scroll inside their own containers rather than pushing the page sideways.

Yes. Every category, every unit and every feature is free, with no account, no sign-up and no limit on how many conversions you run.

No. Everything runs locally in your browser. Your values are never uploaded to our server, never stored, and never sent to an analytics endpoint — there is no backend involved in a conversion at all. The only time a value leaves your machine is if you use the share button, which puts it in a URL and hands it to you to send.

Yes, and the engine is built for it. Each category is a list of units with a factor relating each to a single base unit, so adding pressure, energy, power or fuel economy is a data change rather than new conversion code. Temperature is the only case that needs anything more, because its scales have offsets as well as different degree sizes.