Unit converter
US MPG to UK MPG.
Convert mpg (US) to mpg (UK) and mpg (UK) to mpg (US). Type in either box and the other follows. Same car, same fuel, two different numbers — because the US gallon is a fifth smaller than the imperial one.
| mpg (US) | mpg (UK) |
|---|---|
| 15 mpg (US) | 18.0142 mpg (UK) |
| 20 mpg (US) | 24.019 mpg (UK) |
| 25 mpg (US) | 30.0237 mpg (UK) |
| 30 mpg (US) | 36.0285 mpg (UK) |
| 35 mpg (US) | 42.0332 mpg (UK) |
| 40 mpg (US) | 48.038 mpg (UK) |
| 45 mpg (US) | 54.0427 mpg (UK) |
| 50 mpg (US) | 60.0475 mpg (UK) |
| 60 mpg (US) | 72.057 mpg (UK) |
| 70 mpg (US) | 84.0665 mpg (UK) |
- Conversion goes through L/100 km in both directions, so neither figure is rounded on the way.
Definitions
- Miles per US gallon uses the smaller 3.785 41 L gallon, so a car rated 40 mpg in the US is about 48 mpg in the UK.
- 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. 1 mpg (US) = 1.200949926 mpg (UK).
- 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
One direction multiplies and the other divides by the same number, so nothing is lost by going back and forth.
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: how many miles per imperial gallon in a miles per us gallon (1.20095), how many miles per US gallon in a miles per imperial gallon (0.832674), and what 30 mpg (US) is in miles per imperial gallon (36.0285 mpg (UK)).
- Fuel economy converter
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- UK MPG to litres per 100 kilometres
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