Convert mile per us gallons to mile per imperial gallons

1 mpg (US) = 1.2009499255 mpg (imp) — exactly. Both units are defined against the SI, so this factor is a fraction, not an approximation.

From

1.200 949 925 5mpg (imp)

≈ Rounded to 12 s.f. 1 mpg (US) ≈ 1.200 949 925 5 mpg (imp)

As a fraction: 568261250/473176473

Significant digits 12 Notation 1 mpg (US) = 1.2009499255 mpg (imp)

How to convert mile per us gallons to mile per imperial gallons

Multiply the number of mile per us gallons by 1.2009499255 to get mile per imperial gallons.

Mile per US gallon: The US EPA figure.

Mile per imperial gallon: UK figures use the larger imperial gallon, so they look about 20% better than US ones for the same car.

Mile per US gallons (mpg (US))	Mile per imperial gallons (mpg (imp))
1 mpg (US)	1.200 949 9
2 mpg (US)	2.401 899 9
3 mpg (US)	3.602 849 8
4 mpg (US)	4.803 799 7
5 mpg (US)	6.004 749 6
10 mpg (US)	12.009 499
15 mpg (US)	18.014 249
20 mpg (US)	24.018 999
25 mpg (US)	30.023 748
30 mpg (US)	36.028 498
40 mpg (US)	48.037 997
50 mpg (US)	60.047 496

Mile per imperial gallons (mpg (imp))	Mile per US gallons (mpg (US))
1 mpg (imp)	0.832 674 18
2 mpg (imp)	1.665 348 4
3 mpg (imp)	2.498 022 6
4 mpg (imp)	3.330 696 7
5 mpg (imp)	4.163 370 9
10 mpg (imp)	8.326 741 8
15 mpg (imp)	12.490 113
20 mpg (imp)	16.653 484
25 mpg (imp)	20.816 855
30 mpg (imp)	24.980 226
40 mpg (imp)	33.306 967
50 mpg (imp)	41.633 709

One mile per us gallon equals 1.200949926 mile per imperial gallons (mpg (US) → mpg (imp)). That figure is exact, not rounded.

Multiply the number of mile per us gallons by 1.2009499255 to get mile per imperial gallons.

One mile per imperial gallon is 0.8326741846 mile per us gallons.

10 mpg (US) = 12.009 499 mpg (imp).

The US EPA figure.

UK figures use the larger imperial gallon, so they look about 20% better than US ones for the same car.