Unit Converter
Convert length, mass, temperature, area, volume, speed, time, data, pressure and energy units with exact definitions and a table of all units. Free.
| Nanometer (nm) | 1,000,000,000 |
|---|---|
| Micrometer (µm) | 1,000,000 |
| Millimeter (mm) | 1,000 |
| Centimeter (cm) | 100 |
| Meter (m) | 1 |
| Kilometer (km) | 0.001 |
| Inch (in) | 39.3700787402 |
| Foot (ft) | 3.28083989501 |
| Yard (yd) | 1.09361329834 |
| Mile (mi) | 0.000621371192237 |
| Nautical mile (nmi) | 0.000539956803456 |
Exact definitions: 1 in = 2.54 cm, 1 ft = 0.3048 m, 1 mi = 1609.344 m (international yard, 1959), 1 nmi = 1852 m.
What is Unit Converter?
Convert values between about 100 units in ten quantities: length, mass, temperature, area, volume, speed, time, digital storage, pressure and energy. You get the selected conversion plus a table with the value in every unit of the quantity.
How to use Unit Converter
- Choose the Quantity (for example Length or Temperature).
- Enter the Value; both
1.5and1,5are accepted where a comma is the local decimal separator. - Select the From and To units, or swap them with ⇄.
- Read the result and the All units table; copy the result with Copy.
Example
1 bar → psi
14.503773773 psi
1 psi = 0.45359237 kg × 9.80665 m/s² ÷ (0.0254 m)² ≈ 6894.757 Pa.
When to use Unit Converter
Use it for everyday, engineering and computing conversions. Months and years are averages (Julian year of 365.25 days), so do not use them for calendar date math; cooking units are US customary, not metric or imperial cups.
How Unit Converter works
Every linear unit is stored as an exact factor to the SI base unit (metre, kilogram, square metre, cubic metre, metre per second, second, byte, pascal, joule), using the legal definitions: 1 in = 0.0254 m, 1 lb = 0.45359237 kg, 1 US gallon = 231 in³, 1 atm = 101 325 Pa, 1 cal = 4.184 J, 1 BTU (IT) = 1055.05585262 J. A conversion is value × factor(from) ÷ factor(to). Temperatures go through kelvin with offsets (K = °C + 273.15, °F = °C × 9/5 + 32, °R = K × 9/5). Results are shown with up to 12 significant digits to hide floating-point noise.
Common Use Cases
- Convert a recipe from US cups and ounces to millilitres and grams
- Check a tyre pressure in bar vs psi
- Convert a download size from GB to GiB
- Turn a speed limit from km/h into mph
- Convert kWh of electricity to kcal or BTU
FAQs
What is the difference between GB and GiB?
GB is decimal (1 000 000 000 bytes); GiB is binary (1 073 741 824 bytes). Operating systems often show GiB but label it GB.
Which gallon and cup are used?
US customary units (gallon = 3.785411784 L, cup = 236.5882365 mL). The UK (imperial) gallon is listed separately.
Why can't I enter −300 °C?
That is below absolute zero (−273.15 °C), which is physically impossible, so the tool shows an error.
Is "ton" metric?
The list has metric tonne (t, 1000 kg), US short ton (2000 lb) and UK long ton (2240 lb) as separate units.