How to convert US mpg to imperial mpg
Multiply by 1.2009, the ratio of the two gallons. For mental arithmetic, add a fifth: 30 US mpg is about 36 imperial mpg, and 40 is 48.
Where these two units are used
The mile per US gallon measures an economy, so the higher the better, and it is worked out on the gallon of 3.785 liters. The mile per imperial gallon rests on a gallon a fifth larger: the same car scores about twenty per cent better on it, having changed nothing at all. Same name, same symbol, twenty per cent apart: the imperial gallon is 4.546 liters against 3.785 for the American one, and a brochure that fails to say which is lying by omission.
US mpg to imperial mpg conversion table
| 15 mpg | 18.01 mpg UK |
| 20 mpg | 24.02 mpg UK |
| 25 mpg | 30.02 mpg UK |
| 30 mpg | 36.03 mpg UK |
| 35 mpg | 42.03 mpg UK |
| 40 mpg | 48.04 mpg UK |
| 45 mpg | 54.04 mpg UK |
| 50 mpg | 60.05 mpg UK |
| 60 mpg | 72.06 mpg UK |
| 70 mpg | 84.07 mpg UK |
| 100 mpg | 120.09 mpg UK |
Show every value
- 1 mpg = 1.201 mpg UK
- 2 mpg = 2.402 mpg UK
- 3 mpg = 3.603 mpg UK
- 4 mpg = 4.804 mpg UK
- 5 mpg = 6.005 mpg UK
- 6 mpg = 7.206 mpg UK
- 7 mpg = 8.407 mpg UK
- 8 mpg = 9.608 mpg UK
- 9 mpg = 10.809 mpg UK
- 10 mpg = 12.009 mpg UK
- 11 mpg = 13.21 mpg UK
- 12 mpg = 14.411 mpg UK
- 13 mpg = 15.612 mpg UK
- 14 mpg = 16.813 mpg UK
- 15 mpg = 18.014 mpg UK
- 16 mpg = 19.215 mpg UK
- 17 mpg = 20.416 mpg UK
- 18 mpg = 21.617 mpg UK
- 19 mpg = 22.818 mpg UK
- 20 mpg = 24.019 mpg UK
- 21 mpg = 25.22 mpg UK
- 22 mpg = 26.421 mpg UK
- 23 mpg = 27.622 mpg UK
- 24 mpg = 28.823 mpg UK
- 25 mpg = 30.024 mpg UK
- 26 mpg = 31.225 mpg UK
- 27 mpg = 32.426 mpg UK
- 28 mpg = 33.627 mpg UK
- 29 mpg = 34.828 mpg UK
- 30 mpg = 36.028 mpg UK
- 31 mpg = 37.229 mpg UK
- 32 mpg = 38.43 mpg UK
- 33 mpg = 39.631 mpg UK
- 34 mpg = 40.832 mpg UK
- 35 mpg = 42.033 mpg UK
- 36 mpg = 43.234 mpg UK
- 37 mpg = 44.435 mpg UK
- 38 mpg = 45.636 mpg UK
- 39 mpg = 46.837 mpg UK
- 40 mpg = 48.038 mpg UK
- 41 mpg = 49.239 mpg UK
- 42 mpg = 50.44 mpg UK
- 43 mpg = 51.641 mpg UK
- 44 mpg = 52.842 mpg UK
- 45 mpg = 54.043 mpg UK
- 46 mpg = 55.244 mpg UK
- 47 mpg = 56.445 mpg UK
- 48 mpg = 57.646 mpg UK
- 49 mpg = 58.847 mpg UK
- 50 mpg = 60.047 mpg UK
- 51 mpg = 61.248 mpg UK
- 52 mpg = 62.449 mpg UK
- 53 mpg = 63.65 mpg UK
- 54 mpg = 64.851 mpg UK
- 55 mpg = 66.052 mpg UK
- 56 mpg = 67.253 mpg UK
- 57 mpg = 68.454 mpg UK
- 58 mpg = 69.655 mpg UK
- 59 mpg = 70.856 mpg UK
- 60 mpg = 72.057 mpg UK
- 61 mpg = 73.258 mpg UK
- 62 mpg = 74.459 mpg UK
- 63 mpg = 75.66 mpg UK
- 64 mpg = 76.861 mpg UK
- 65 mpg = 78.062 mpg UK
- 66 mpg = 79.263 mpg UK
- 67 mpg = 80.464 mpg UK
- 68 mpg = 81.665 mpg UK
- 69 mpg = 82.866 mpg UK
- 70 mpg = 84.066 mpg UK
- 71 mpg = 85.267 mpg UK
- 72 mpg = 86.468 mpg UK
- 73 mpg = 87.669 mpg UK
- 74 mpg = 88.87 mpg UK
- 75 mpg = 90.071 mpg UK
- 76 mpg = 91.272 mpg UK
- 77 mpg = 92.473 mpg UK
- 78 mpg = 93.674 mpg UK
- 79 mpg = 94.875 mpg UK
- 80 mpg = 96.076 mpg UK
- 81 mpg = 97.277 mpg UK
- 82 mpg = 98.478 mpg UK
- 83 mpg = 99.679 mpg UK
- 84 mpg = 100.88 mpg UK
- 85 mpg = 102.081 mpg UK
- 86 mpg = 103.282 mpg UK
- 87 mpg = 104.483 mpg UK
- 88 mpg = 105.684 mpg UK
- 89 mpg = 106.885 mpg UK
- 90 mpg = 108.085 mpg UK
- 91 mpg = 109.286 mpg UK
- 92 mpg = 110.487 mpg UK
- 93 mpg = 111.688 mpg UK
- 94 mpg = 112.889 mpg UK
- 95 mpg = 114.09 mpg UK
- 96 mpg = 115.291 mpg UK
- 97 mpg = 116.492 mpg UK
- 98 mpg = 117.693 mpg UK
- 99 mpg = 118.894 mpg UK
- 100 mpg = 120.095 mpg UK
- 110 mpg = 132.104 mpg UK
- 120 mpg = 144.114 mpg UK
- 130 mpg = 156.123 mpg UK
- 140 mpg = 168.133 mpg UK
- 150 mpg = 180.142 mpg UK
- 160 mpg = 192.152 mpg UK
- 170 mpg = 204.161 mpg UK
- 180 mpg = 216.171 mpg UK
- 190 mpg = 228.18 mpg UK
- 200 mpg = 240.19 mpg UK
The US gallon is exactly 3.785411784 liters and the imperial gallon exactly 4.54609 liters; the ratio follows from those two figures. Methodology & sources.
Frequently asked questions
Why is the British gallon larger?
Because the two countries froze two different gallons two centuries apart. The United States kept the Queen Anne wine gallon, fixed in 1707 at 231 cubic inches, that is 3.785411784 liters. The United Kingdom defined a single imperial gallon in 1824 as the volume of ten pounds of water, that is 4.54609 liters. The gap is 20.095 %, and it has never closed.
A car rated 40 mpg in the UK, what is it in the US?
33.3 US mpg. The direction misleads: the car does not become less frugal, the reference gallon shrinks. The same car burns 7.06 liters per hundred kilometers either way, which is exactly why Europe counts in liters per hundred kilometers, a unit that depends on no gallon at all.
How do you tell which mpg a figure is?
By the country of the source. Figures from the American EPA and from US manufacturers' sheets are in US gallons. British and Irish brochures, and WLTP cycles published there, are in imperial gallons. When in doubt, the safest cross-check runs through consumption: 235.21 divided by the mpg gives liters per hundred kilometers if the gallon is American, 282.48 if it is British.
Does Canada use imperial mpg?
When a Canadian says mpg, they mean the imperial gallon, a legacy from before the metrication of the 1970s. But the official display, that of Natural Resources Canada and of fuel labels, has been in liters per hundred kilometers since then. A vehicle sold on both sides of the border therefore carries two different figures for one identical consumption.
How many liters per 100 km is one imperial mpg?
Divide 282.48 by the number of imperial mpg. Forty imperial mpg is 7.06 l/100 km, fifty is 5.65 and sixty is 4.71. The American constant is 235.21, and those two numbers stand in the same 1.2009 ratio as the gallons they come from.