The British Imperial system of units of capacity was established in 1824 in Britain by the Weights and Measures Act. Unlike the standards for such measurements as length or weight, the capacity units were considerably different from the traditional units that preceded them. The new Imperial gallon was defined as the volume of water weighing 10 pounds at 62° F. This is considerably larger than the United States customary gallon and indeed larger than most gallons that had existed in Britain at the time, which were based on a measure holding 8 pounds of a specified commodity.

Unlike the capacity units of the United States customary system, the Imperial gallon was used as a base unit for both liquid and dry commodities, and the bushel, which in the United States is the base unit for dry commodities, is in British Imperial measure simply a subsidiary unit defined as 8 gallons.