Gallon Gallon The gallon () is a unit of measurement for volume and fluid capacity in both the US customary units and the British imperial systems of measurement. Three significantly different sizes are in current use: the imperial gallon defined as litres (4 imperial quarts or 8 imperial pints), which is used in the United Kingdom, Canada, and some Caribbean nations; the US gallon defined as 231 cubic inches (4 US liquid quarts or 8 US liquid pints) or about , which is used in the US and some Latin American and Caribbean countries; and the least-used US dry gallon defined
Gallon works out at approximately (). The metric definition of exactly cubic decimetres (also after the litre was redefined in 1964, ≈ ) was adopted shortly afterwards in Canada, but from 1976 the conventional value of was used in the United Kingdom until the Canadian convention was adopted in 1985. Historically, gallons of various sizes were used in many parts of Western Europe. In these localities, it has been replaced as the unit of capacity by the litre. Gallon The gallon () is a unit of measurement for volume and fluid capacity in both the US customary units and the British