How to use the fuel economy converter
- Type a value in either box. Decimals with a comma or a point both work.
- Choose the units on each side, or press the arrows to swap them.
- The table below shows the value in every unit at once. Click a row to convert to that unit.
About fuel economy units
There are two ways to measure fuel use. Economy (miles per gallon, km per liter) counts distance per unit of fuel, so higher is better. Consumption (liters per 100 km), used in Europe, Canada, Australia and many other countries, counts fuel per distance, so lower is better. They are inverses: to go from US mpg to L/100 km, divide 235.215 by the mpg, so 30 mpg is 7.84 L/100 km.
Gallons differ between countries. A UK gallon is about 20% bigger than a US gallon, so the same car gets a higher mpg figure in the UK: 30 US mpg is 36.03 UK mpg. For UK mpg the L/100 km constant is 282.481 instead of 235.215.
Because the scales are inverse, equal mpg gains do not save equal fuel. Over 100 miles, going from 10 to 20 mpg saves 5 gallons, while going from 30 to 40 mpg saves only 0.83 gallons.
Popular fuel economy conversions
Fuel economy units
| Unit | Symbol | Definition |
|---|---|---|
| Kilometers per liter | km/L | The base unit |
| Miles per gallon | mpg | 1 mpg = 0.4251437074 km/L |
| Miles per gallon | mpg (UK) | 1 mpg (UK) = 0.3540061899 km/L |
| Liters per 100 kilometers | L/100 km | L/100 km = 100 ÷ km/L |
Converting something else? The unit converter covers every kind of unit in one place.