How this calculator works
There is no single gallon. The US liquid gallon is defined as 231 cubic inches, which is 3.785411784 L. The imperial gallon used in the United Kingdom and Canada before metrication is exactly 4.54609 L, about 20 percent larger. Litres are SI-compatible and are the unit on Canadian fuel pumps, so a Canadian litre figure and a US or UK mpg figure need the right gallon when they meet.
Formula
US gal = L / 3.785411784. UK gal = L / 4.54609. L = US gal x 3.785411784 = UK gal x 4.54609. One US gallon is 4 US quarts, and one quart is 0.946352946 L.
Worked example
10 L = 2.64172 US gal = 2.19969 UK gal. 1 L = 0.264172 US gal = 0.219969 UK gal. 50 L = 13.2086 US gal = 10.9985 UK gal. 1 US gal = 3.78541 L, and 1 UK gal = 4.54609 L.
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Frequently asked questions
Which gallon does a Canadian fuel pump use?
Canadian fuel pumps sell in litres. Fuel economy may be quoted in L/100 km, and some older material used the imperial gallon. A US gallon is smaller, so a US mpg figure is lower than a UK mpg figure for the same fuel use.
How do I tell which gallon a recipe means?
US recipes use the US liquid gallon of 3.785 L. British and older Canadian recipes may mean the imperial gallon of 4.546 L. When a recipe is ambiguous, the difference is about 20 percent, so the origin of the recipe is the best clue.
Is a US gallon the same as a dry gallon?
No. The US liquid gallon is 231 cubic inches, while the US dry gallon is 268.8025 cubic inches, about 4.405 L. Dry gallons are used for some agricultural commodities and are not on this page.
Why is the imperial gallon larger?
The imperial gallon was defined in 1824 from the volume of 10 pounds of water, which gives 4.54609 L. The US gallon kept an older wine gallon definition of 231 cubic inches.