How to convert imperial gallons to gallons
Formula: gal = gal (UK) × 1.20095
Worked example: 5 gal (UK) → 5 × 1.20095 = 6.00475 gal
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.
Imperial gallons to gallons conversion chart
| Imperial gallons (gal (UK)) | Gallons (gal) |
|---|---|
| 1 gal (UK) | 1.20095 gal |
| 2 gal (UK) | 2.4019 gal |
| 3 gal (UK) | 3.60285 gal |
| 4 gal (UK) | 4.8038 gal |
| 5 gal (UK) | 6.00475 gal |
| 6 gal (UK) | 7.2057 gal |
| 7 gal (UK) | 8.40665 gal |
| 8 gal (UK) | 9.6076 gal |
| 9 gal (UK) | 10.8085 gal |
| 10 gal (UK) | 12.0095 gal |
| 12 gal (UK) | 14.4114 gal |
| 15 gal (UK) | 18.0142 gal |
| 20 gal (UK) | 24.019 gal |
| 25 gal (UK) | 30.0237 gal |
| 30 gal (UK) | 36.0285 gal |
| 40 gal (UK) | 48.038 gal |
| 50 gal (UK) | 60.0475 gal |
| 75 gal (UK) | 90.0712 gal |
| 100 gal (UK) | 120.095 gal |
| 250 gal (UK) | 300.237 gal |
| 500 gal (UK) | 600.475 gal |
| 1,000 gal (UK) | 1,200.95 gal |
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.
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.