Glossary
Brewer’s barrel
A unit of brewing volume: 36 imperial gallons (about 164 litres) in Britain, but 31 US gallons (about 117 litres) in the United States.
Also called barrel, bbl.
Commonly misunderstood
A "20-barrel brewery" means something substantially different in Britain and America. The units differ by about 40%, and the figure is meaningless without knowing which is meant.
Related
- Firkin — The cask size actually used in trade.
More vocabulary
Beer-clean glass · Cask · Cellar conditioning · Crowler · Draught · Firkin · Growler · Imperial pint · Keg · KeyKeg
See every term on the glossary index.
Last reviewed 2026-08-16.
Evidence
What BeerHQ knows about this, and how. Every statement carries the state of the evidence behind it rather than being presented flatly as fact.
A brewer’s barrel in British usage is 36 imperial gallons, and UK duty guidance works in 163.7 litres for one — which is what 36 imperial gallons comes to. The American barrel is a different unit entirely at 31 US gallons, so the word means roughly 164 litres on one side of the Atlantic and roughly 117 on the other.
Checked against the source Applies in United Kingdom.
Source: Alcoholic products technical guide — Section 13, measurement of quantity, section 13.10, worked example (Published 11 December 2024, updated 12 August 2026)