Beer measures

The first thing that needs to be said on this subject is that there's only one size of beer barrel, and it holds 36 gallons. All other containers that beer is sold in (in bulk) are more properly referred to as casks or kegs.

The subject of how much each container holds is, I believe, one that's best for quizzers not to over–think. If you want to cut straight to the chase, please go to the table at the bottom of this page; but a little background information might help to explain why this topic is more complicated than it may appear at first sight.

The basic size of cask is the firkin, which today holds 9 gallons. All other casks are multiples (or divisions) of a firkin. A firkin was defined in the year 1454 as 9 gallons for beer and 8 gallons for ale. (Historically, beer differs from ale in that hops are used in the brewing process. Hopped beer was first imported to Britain from Holland in about 1400, and it wasn't until 1524 that hops were first introduced to Kent by Dutch farmers.)

In 1688 the ale firkin was increased to 8.5 gallons, and in 1803 it was brought into line with the beer firkin at 9 gallons. (Wikipedia also gives an alternative story, on the same page, which is that from 1688 the ale and beer firkins were standardised at 8.5 gallons – a typical British compromise, you might say – and this was increased to 9 gallons in 1803.)

Up to this time there were several different types of gallon, including the corn gallon (a.k.a. the Winchester gallon), the ale gallon and the wine gallon. Each of these was defined in terms of cubic inches: 269, 282 and 231 cubic inches respectively. In the current context, needless to say, we are talking about the ale gallon.

In 1824, measurements throughout the British Empire were standardised in what was to be known as the imperial system. The various gallons were replaced by the imperial gallon, which was defined as the volume of 10 lbs of water at standard temperature and pressure (30 inches of mercury at 62 °F or 17 °C). This definition was refined in 1963, but in 1985 the imperial gallon was redefined as exactly 4.54609 litres.

It would be a very demanding question setter that asked you anything about the times before 1824, but for the record the following table summarises:

Years	Litres in a gallon	Gallons in a firkin
			Ale		Beer
1454–1688	4.621		8		9
1688–1803			8.5		9 (or 8.5)
1803–1824			9		9
Since 1824	4.546		9		9

And, lastly but by no means leastly: the following table compares the size of each cask with the firkin (which is the basic measure, as we saw above) and the barrel (in case you get asked something like "How many barrels are equivalent to a hogshead?"). But these figures are really little more than an aide–memoire; all that the quizzer really needs to worry about is the final column, which gives the number of gallons in each type of cask.

Cask		Firkins		Barrels		Gallons
Pin		0.5		0.125		4.5
Firkin		1		0.25		9
Kilderkin		2		0.5		18
Barrel		4		1		36
Hogshead		6		1.5		54
Butt		12		3		108
Tun		24		6		216

(Mathematicians will notice that the number of gallons in a tun is six cubed.)

If you've followed the narrative above, you'll appreciate that up to 1803 the figures were slightly different (for ale, and, if you believe one of Wikipedia's versions, for beer between 1688 and 1803). If ever you need to, you can use the first table (above) to calculate these figures: for example, between 1454 and 1688 there were 6 x 8 = 48 gallons in a hogshead of ale.

© Haydn Thompson 2017–21