Imperial gallons to US gallons Converter

About this calculator

The imperial gallon (used in the UK, Canada, and historically the Commonwealth) and the US gallon are different volumes despite sharing a name: 1 imperial gallon = 4.54609 litres, while 1 US gallon = 3.78541 litres, making 1 imperial gallon ≈ 1.20095 US gallons. The imperial gallon was originally defined as the volume of 10 pounds of water; the US gallon derives from an older English wine gallon.

The mismatch matters most in fuel economy figures — a car rated at 40 mpg in the UK is not achieving 40 mpg by US standards, since the same distance is being divided by a larger gallon — as well as in recipe conversion, fuel tank capacities, and any cross-border trade in liquids where UK/Canadian and US specifications are quoted in "gallons" without clarifying which one.