How to convert gallons to imperial gallons
Formula: gal (UK) = gal × 0.832674
Worked example: 5 gal → 5 × 0.832674 = 4.16337 gal (UK)
An imperial gallon is 20% larger than a US gallon, so a US gallon is only 0.833 imperial gallon. This is why a car rated 30 mpg in the US shows about 36 mpg in the UK: the fuel economy did not change, only the gallon did.
Gallons to imperial gallons conversion chart
| Gallons (gal) | Imperial gallons (gal (UK)) |
|---|---|
| 1 gal | 0.832674 gal (UK) |
| 2 gal | 1.66535 gal (UK) |
| 3 gal | 2.49802 gal (UK) |
| 4 gal | 3.3307 gal (UK) |
| 5 gal | 4.16337 gal (UK) |
| 6 gal | 4.99605 gal (UK) |
| 7 gal | 5.82872 gal (UK) |
| 8 gal | 6.66139 gal (UK) |
| 9 gal | 7.49407 gal (UK) |
| 10 gal | 8.32674 gal (UK) |
| 12 gal | 9.99209 gal (UK) |
| 15 gal | 12.4901 gal (UK) |
| 20 gal | 16.6535 gal (UK) |
| 25 gal | 20.8169 gal (UK) |
| 30 gal | 24.9802 gal (UK) |
| 40 gal | 33.307 gal (UK) |
| 50 gal | 41.6337 gal (UK) |
| 75 gal | 62.4506 gal (UK) |
| 100 gal | 83.2674 gal (UK) |
| 250 gal | 208.169 gal (UK) |
| 500 gal | 416.337 gal (UK) |
| 1,000 gal | 832.674 gal (UK) |
What is a gallon?
The US gallon is defined as 231 cubic inches, exactly 3.785411784 liters, and holds 4 quarts or 128 fluid ounces. Gasoline, milk, paint and water use in the United States are measured in gallons.
What is an imperial gallon?
The imperial gallon is exactly 4.54609 liters, about 20% more than the US gallon. British fuel economy figures in miles per gallon use it, which is why UK mpg numbers look higher than US ones for the same car.