Unit converter
Litres per 100 kilometres to UK MPG.
Convert L/100 km to mpg (UK) and mpg (UK) to L/100 km. Type in either box and the other follows. Official UK figures give both, and the relationship is a division rather than a scale factor.
| L/100 km | mpg (UK) |
|---|---|
| 3 L/100 km | 94.1603 mpg (UK) |
| 4 L/100 km | 70.6202 mpg (UK) |
| 5 L/100 km | 56.4962 mpg (UK) |
| 6 L/100 km | 47.0802 mpg (UK) |
| 7 L/100 km | 40.3544 mpg (UK) |
| 8 L/100 km | 35.3101 mpg (UK) |
| 9 L/100 km | 31.3868 mpg (UK) |
| 10 L/100 km | 28.2481 mpg (UK) |
| 12 L/100 km | 23.5401 mpg (UK) |
| 15 L/100 km | 18.8321 mpg (UK) |
| 20 L/100 km | 14.124 mpg (UK) |
- L/100 km and mpg (UK) are reciprocals of one another: as one rises the other falls.
Definitions
- Litres per 100 km measures consumption: lower is better. It is the figure EU and UK official documents lead with.
- Miles per imperial gallon measures economy: higher is better. UK brochures use it, and the imperial gallon is 4.546 09 L.
- This conversion is exact by definition. L/100 km × mpg (UK) = 282.4809363.
- Fuel economy is reciprocal: more miles per gallon is less fuel per 100 km. A US gallon is smaller than an imperial gallon, so US mpg and UK mpg are different numbers for the same car.
How it works
These two units run in opposite directions, so this is a division rather than a multiplication. Doubling one does not double the other; it halves it.
The value passes through L/100 km, the unit every other fuel economy unit on the site is defined against, rather than a number written into this page on its own. That is why the figure here, the figure in the table above and the general fuel economy converter always agree.
Display precision limits significant figures rather than decimal places, which matters here because a reciprocal magnifies rounding: a figure trimmed at one end of the scale moves further at the other. Only the display is rounded. The editable box always holds a plain number at full working precision, so you can carry on from either side.
Common questions this answers: what 6 L/100 km is in miles per imperial gallon (47.0802 mpg (UK)), what halving it does (94.1603 mpg (UK), not half of 47.0802), and which way round the units run — a higher L/100 km always means a lower mpg (UK).
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