🔄 Unit Converter
Enter one value and see it in every unit of the same type at once — US, metric, UK and even Korean units.
Key conversion factors to remember
| Type | Handy relationships |
|---|---|
| Length | 1 in = 2.54 cm · 1 ft = 30.48 cm · 1 m ≈ 3.281 ft · 1 mi ≈ 1.609 km |
| Weight | 1 kg ≈ 2.2046 lb · 1 lb ≈ 453.6 g · 1 oz ≈ 28.35 g · 1 st = 14 lb |
| Area | 1 m² ≈ 10.764 sq ft · 1 acre = 43,560 sq ft · 1 ha ≈ 2.471 acres · 1 pyeong ≈ 3.306 m² |
| Volume | 1 US gal ≈ 3.785 L · 1 US cup ≈ 236.6 mL · 1 fl oz ≈ 29.57 mL · 1 UK gal = 4.546 L |
| Temperature | °F = °C × 9/5 + 32 · °C = (°F − 32) × 5/9 · K = °C + 273.15 |
| Speed | 1 mph ≈ 1.609 km/h · 1 m/s = 3.6 km/h · 1 knot = 1.852 km/h |
| Data | 1 GB = 10⁹ B · 1 GiB = 2³⁰ B ≈ 1.074 GB · 1 byte = 8 bits |
How to use the unit converter
- Pick a type — length, weight, area, volume, temperature, speed or data size.
- Enter a value and choose the unit you are converting from. The result panel converts it into every unit of that type at once.
- The unit chosen under To is shown as the big number. Use ⇄ to flip the direction.
It covers US customary units (inches, feet, miles, pounds, ounces, cups, gallons, °F, mph), metric/SI units, UK units like stone and the imperial gallon, and a few traditional Korean units such as the pyeong used for apartment sizes in Korea.
How the conversion works
Every unit is stored as a multiple of one base unit per type (meter, kilogram, square meter, liter, meter per second, byte). A conversion always goes "from unit → base unit → target unit":
result = value × (factor of the from-unit) ÷ (factor of the to-unit)
Temperature is the exception. Celsius, Fahrenheit and Kelvin have different zero points, so the formula needs an addition as well as a multiplication: °F = °C × 9/5 + 32 and K = °C + 273.15.
US customary and metric units are linked by exact legal definitions: since 1959 an inch is exactly 2.54 cm and a pound is exactly 0.45359237 kg. That means inch-to-cm and pound-to-kg conversions have no built-in error; any difference you see elsewhere comes from rounding.
US vs. UK (imperial) units
- Gallons — a US gallon is 3.785 L, an imperial (UK) gallon is 4.546 L, about 20% larger. UK fuel-economy figures in MPG therefore look higher than US ones for the same car.
- Fluid ounces and pints — a US pint is 16 fl oz (473 mL), a UK pint is 20 imperial fl oz (568 mL).
- Tons — the US short ton is 2,000 lb (907 kg); the metric tonne is 1,000 kg; the UK long ton is 2,240 lb.
- Stone — 14 lb, still used for body weight in the UK and Ireland.
Why does my 1 TB drive show 931 GB?
Drive makers count 1 TB as 10¹² bytes (decimal), while Windows reports size in binary units of 1,024 (technically GiB, though it labels them "GB"). 10¹² ÷ 1024³ ≈ 931.3, so nothing is missing. Try Data size → TB to GiB to check. Internet speeds such as "100 Mbps" are in bits, which is 12.5 megabytes per second.
Mach is approximated with the speed of sound at sea level and 15 °C (about 340.29 m/s); the real value changes with temperature and altitude. Results are rounded to at most 7 significant digits.