Convert MPG (US) to MPG (UK) instantly — enter a value in either field.
| MPG (US) (mpg (US)) | MPG (UK) (mpg (UK)) |
|---|---|
| 15 mpg (US) | 18 mpg (UK) |
| 20 mpg (US) | 24 mpg (UK) |
| 25 mpg (US) | 30 mpg (UK) |
| 30 mpg (US) | 36 mpg (UK) |
| 35 mpg (US) | 42 mpg (UK) |
| 40 mpg (US) | 48 mpg (UK) |
| 45 mpg (US) | 54 mpg (UK) |
| 50 mpg (US) | 60 mpg (UK) |
| 55 mpg (US) | 66.1 mpg (UK) |
| 60 mpg (US) | 72.1 mpg (UK) |
Example: 30 mpg (US) → 30 × 1.20095 = 36.0 mpg (UK)
The United States and the United Kingdom both measure fuel economy in “miles per gallon,” but their gallons are different sizes. The US liquid gallon is exactly 3.785411784 litres; the imperial gallon is 4.54609 litres — about 20.09% larger. Because the imperial gallon is bigger, a car always shows a higher mpg figure on the UK scale.
The conversion is linear: mpg (UK) = mpg (US) × 1.20095. A car rated 30 mpg in the US shows 36.0 mpg on the UK scale. A 50-mpg US rating translates to 60 UK mpg. No physical efficiency has changed; only the unit of volume has.
This distinction matters when comparing cross-market car reviews. Older British car reviews, some Commonwealth import specs, and classic car fuel economy claims use UK mpg. Modern European cars sold in the UK are typically rated in L/100km for regulatory purposes but may also list UK mpg for consumer familiarity.
The UK (imperial) gallon (4.546 L) is larger than the US gallon (3.785 L). A car uses the same volume of fuel for a given journey, but that volume fills a larger share of the smaller US gallon, so fewer miles per US gallon result.
30 × 1.20095 = 36.0 mpg UK. The conversion factor is 4.54609 ÷ 3.785411784 = 1.20095.
Since 2011, European cars (including UK models) must state fuel economy in L/100km under regulation. Mpg figures in UK car reviews are typically calculated from the L/100km WLTP figure. US mpg figures come from EPA testing on a different drive cycle.