Tun (volume)

The tun is an old English unit of wine cask volume, holding about 954 litres, almost a cubic metre. Etymologically it is identical to the ton, a unit of mass or weight. Originally, it was a genuine unit of volume and measured 256 gallons (2⁸), which is the base for the name of the quarter of 64 corn gallons. Its later division into 210 imperial or 252 wine gallons was chosen to be evenly divisible by small integers, including seven:; 210 := 2 · 3 · 5 · 7; 252 := 2² · 3² · 7
Queen Anne’s wine gallon is 231 cubic inches (3 × 7 × 11 in³), which makes the tun based on it exactly 2² · 3³ · 7² · 11 = 58,212 in³, which is a cylinder with diameter and height of 42 in both.

It is assumed that the tun once also was the base for English brewery casks, whose now largest measure, the hogshead, is of a similar magnitude as its wine equivalent (between 220 and 250 litres). A different gallon was used for ale and beer, the ale gallon, which in modern times was 282 cubic inches (2 · 3 · 47 in³), which does not divide the 58,212 in³ nicely.

There also were other, sometimes foreign tuns/tons, for example at least until the 16th century one of 240 gallons, grouped in sixty sesters of four gallons each.

ee also

* Cubic ton