Question: what is the difference between a us gallon and an imperial gallon?
Answer: the imperial gallon ("impgal"), defined as 4.54609 litres, which is used in the United Kingdom, Canada, and some Caribbean nations; the US gallon ("usgal") defined as 231 cubic inches (exactly 3.785411784 litres), which is used in the US and some Latin American and Caribbean countries; and.