Fuel Economy Converter
Convert fuel economy between consumption (L/100km) and efficiency (mpg, km/L) units.
From
To
1 mpg (US) =
| Liters per 100 km | 235.214583 L/100km |
| Kilometers per liter | 0.425144 km/L |
| Miles per gallon (UK) | 1.20095 mpg (UK) |
About this calculator
Fuel economy can be expressed two ways. Consumption units like liters per 100 kilometers (L/100km) measure how much fuel is used over a fixed distance — lower is better. Efficiency units like miles per gallon (mpg) or kilometers per liter measure how far you travel per unit of fuel — higher is better. The two are inversely related, which is why this converter uses reciprocal functions rather than simple multiplication.
The base unit is L/100km. To convert, km/L = 100 / (L/100km), US mpg = 235.214583 / (L/100km), and UK mpg = 282.480936 / (L/100km). Because US and UK gallons differ in size, US and UK mpg figures are not interchangeable — the same car gets a higher number in UK mpg.
Frequently asked questions
For US mpg, divide 235.214583 by the mpg value. For example, 30 US mpg equals about 7.84 L/100km.
A UK (imperial) gallon is larger than a US gallon, so the same fuel use gives a higher UK mpg figure. US mpg uses 235.214583 and UK mpg uses 282.480936 as the conversion constant.
For L/100km, lower is more efficient. For mpg and km/L, higher is more efficient — they measure opposite things.
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