Fuel economy
How to convert fuel economy
MPG measures distance per fuel used, while L/100 km measures fuel used per distance. Because they are reciprocals, the conversion uses division rather than simple multiplication.
Open the fuel economy converterConvert US MPG and L/100 km
L/100 km = 235.214583 ÷ US MPG
A car rated at 30 US MPG uses about 7.84 L/100 km. To reverse the conversion, divide 235.214583 by the L/100 km value.
Imperial MPG uses a larger gallon
An imperial gallon is larger than a US liquid gallon, so the same vehicle has a higher numerical imperial MPG. Use 282.480936 as the reciprocal constant for imperial MPG and L/100 km.
For example, 40 imperial MPG converts to about 7.06 L/100 km. It is about 33.31 US MPG, not 40 US MPG.
Understand which direction means better economy
Higher MPG means better fuel economy. Lower L/100 km means better fuel economy. A result that moves both numbers in the same “better” direction is a warning that the reciprocal step was missed.
Practical checks
- Confirm whether MPG is US or imperial.
- Do not convert zero L/100 km or zero MPG by division.
- Treat published ratings as standardized comparisons; real consumption varies with driving and conditions.
Convert with ToolPixels
The free Fuel Economy Converter converts the supported units in your browser. Enter a value, choose the source and target units, select the needed precision, and review the displayed formula before using the result.