The unit converter changes measurements between metric and imperial (US customary) units across six categories: length, weight, temperature, area, volume and speed. Pick a category, type a value and you see the converted figure instantly, plus a table of the same value in every other unit in that category.
How to use it
- Choose what you are measuring.
- Enter the value and pick the units to convert from and to.
- Use “Swap units” to reverse the direction.
Handy conversion factors
- 1 inch = 2.54 cm exactly, so 1 foot = 30.48 cm and 1 mile = 1.609344 km.
- 1 pound = 0.45359237 kg exactly, and 1 kg ≈ 2.2046 lb.
- 1 US gallon = 3.785411784 litres; a UK (imperial) gallon is larger at 4.54609 litres.
- 1 square metre ≈ 10.764 square feet, and 1 acre = 43,560 square feet.
Temperature is different
Temperature scales have different zero points, so you cannot simply multiply:
°F = °C × 9/5 + 32
°C = (°F − 32) × 5/9
K = °C + 273.15
°C = (°F − 32) × 5/9
K = °C + 273.15
A quick mental check: 20 °C is a mild 68 °F, and 30 °C is a hot 86 °F.
Frequently asked questions
Which gallon does the converter use?
Both are available. Choose “US gallon” or “UK gallon” in the volume list.
How precise are the results?
Conversions use exact international definitions where they exist and are shown to up to six significant decimal places.