A barrel is a unit of volume whose size depends on the liquid measured. The most common use is in regard to oil, where prices and quantities are usually referred to by the barrel. In this context, the barrel equals 42 U.S. gallons of liquid. Beer and wine are sometimes also mentioned in barrels. In those contexts, the volume of a barrel may vary between 31 and 36 gallons.
- 55 gallon drum
- Crude oil
- Rainwater catchment and Permaculture
- Water storage in Agriculture, Permaculture and Survivalism
- U.S. Department of Transportation Maritime Administration