How to use this calculator
- Enter or choose quantity.
- Enter or choose value.
- The converted value updates as you type. Use Copy result or Share to keep it.
Method
Result = Value × (size of the “from” unit ÷ size of the “to” unit). Temperatures also shift the zero point: °F = °C × 9/5 + 32, K = °C + 273.15.
- 1 in
- 0.0254 m exactly
- 1 lb
- 0.45359237 kg exactly
- 1 US gal
- 3.785411784 L exactly
- 1 imperial gal
- 4.54609 L exactly
Worked example
- 1 mile = 1,609.344 m by definition, and 1 km = 1,000 m.
- So 1 mi = 1.609344 km.
- 5 × 1.609344 = 8.04672 km.
5 miles is exactly 8.04672 kilometres.
What the result means
Results are shown to 10 significant figures; round them to the precision of your original measurement.
Assumptions and limits
- US customary cups, pints, quarts and gallons differ from imperial ones; both are listed separately.
- Calories are thermochemical (4.184 J); BTU is the International Table BTU (1,055.05585262 J).
- Currency is not converted, because exchange rates change constantly.
- Cooking conversions between volume and weight depend on the ingredient and are not included.
Questions
Why are there two kinds of gallon?
The US gallon is 3.785 L and the imperial (UK) gallon is 4.546 L, about 20% larger. Fluid ounces and pints differ too.
What is the difference between a US ton and a tonne?
A tonne (metric ton) is 1,000 kg; a US (short) ton is 2,000 lb = 907.18 kg; a UK (long) ton is 2,240 lb = 1,016.05 kg.