Because commodities vary in density, the agricultural industry uses to define a bushel for trading purposes. Bushel - Encyclopedia.com

: 1 level bushel equals 2,150.42 cubic inches (roughly 8 gallons or 35.24 liters).

: 1 imperial bushel equals 8 imperial gallons (roughly 36.37 liters).

In the United States, a bushel is primarily a measure of for dry goods, while in the UK, it is used for both liquid and dry items.