True, a US beer barrel is 31 US gallons or 117.3 liters.
The confusing part is that there is also a standard US liquid measure (not for beer) called a barrel that comes in at 31.5 gallons. Then there's the UK barrel which is 36 Imperial gallons (4 imperial - aka 20oz - quarts).
Finally, most European beer producers measure production in hectoliters (100 liters), which is about 4.5 (US) gallons less than a US barrel.
Aren't standard measurements wonderful.
