Gallon and Barrel

Gallon, unit of liquid measure, equal to 3.785 liters, and subdivided into four quarts or eight pints. The imperial gallon used in the United Kingdom and Canada is equivalent to 4.546 liters.

Barrel (measurement), unit of capacity or volume in the United States and the United Kingdom, the definition of which depends on the material being measured. In the United States the dry standard barrel is equivalent to 105 dry qt, or 7056 cu in (116 liters), and a barrel of petroleum is defined as 42 U.S. gallons (159 liters). Various liquid measures containing from 31 to 42 U.S. gallons (119 to 159 liters) are commonly called barrels, however. A barrel of beer in the United Kingdom is defined as 36 imperial gallons (164 liters). See also Weights and Measures.