The beer tun is equal to double the size of a butt: it is therefore exactly 981.95544 litres or approximately 34.677 cubic feet.
[nb 2] [2] The butt of beer is equal to half a tun or two hogsheads, and is therefore exactly 490.97772 litres or approximately 17.339 cubic feet.
[nb 2] The hogshead of beer and ale was equal to a quarter of a tun, half a butt, or three kilderkins.
Ales are usually delivered in firkins, cider and other drinks are usually in boxes, bottles or other containers measured in gallons or litres, and all (except wine) are sold in pints or parts thereof.
Plastic versions of these casks are known as "polypins" and are popular in homebrewing and the off-trade (deliveries for home consumption).