Tun (unit)

The tun (Old English: tunne, Latin: tunellus, Medieval Latin: tunna) is an English unit of liquid volume (not weight), used for measuring wine,^[1] oil or honey. Typically a large vat or vessel, most often holding 252 wine gallons, but occasionally other sizes (e.g. 256, 240 and 208 gallons) were also used.^[2] The modern tun is about 954 litres.

The word tun is etymologically related to the word ton for the unit of mass, the mass of a tun of wine being approximately one long ton, which is 2240 pounds (1016 kg). The spellings "tun" and "ton" were sometimes used interchangeably.^[3]

History

Originally, the tun was defined as 256 wine gallons;^{[nb 1]} this is the basis for the name of the quarter of 64 corn gallons. At some time before the 15th century, it was reduced to 252 wine gallons, so as to be evenly divisible by other small integers, including seven.^{[nb 2]}

In one Early Modern English example from 1507, a tun is defined as 240 gallons.

He that ys a gawner owght to understonde there ys in a tunne lx systerns and every systern ys iiii galons be yt wyne or oylle.	He that is a gauger ought to understand that there is in a tunne 60 sesters, and every sester is 4 gallons, be it wine or oil.
—Untitled manuscript, consisting of a list of various customs duties, dated 15 July 1507[2][4][5]

With the adoption of the Queen Anne wine gallon of 231 cubic inches in 1706, the tun approximated the volume of a cylinder with both diameter and height of 42 inches.^{[nb 3]} These were adopted as the standard U.S. liquid gallon and tun.

When the imperial system was introduced in 1824, the tun was redefined in the UK and its colonies as 210 imperial gallons. The imperial tun remained evenly divisible by small integers.^{[nb 4]} There was also little change in the actual value of the tun.^{[nb 5]}

Standard tuns of wine came to serve as a measure of a ship's capacity.^[6]

		comparisons								historically		imperial definitions			US definitions
measure		tuns	butts	puncheons	hogsheads	tierces	barrels	rundlets		litres[nb 6]		gallons	litres[nb 7]		gallons	litres[nb 8]
tun		1	⁠1/2⁠	⁠1/3⁠	⁠1/4⁠	⁠1/6⁠	⁠1/8⁠	⁠1/14⁠		950–960		210	954.6789		252	953.923769568
butt		2	1	⁠2/3⁠	⁠1/2⁠	⁠1/3⁠	⁠1/4⁠	⁠1/7⁠		475–480		105	477.33945		126	476.961884784
puncheon		3	⁠1+1/2⁠	1	⁠3/4⁠	⁠1/2⁠	⁠3/8⁠	⁠3/14⁠		316–320		70	318.2263		84	317.974589856
hogshead		4	2	⁠1+1/3⁠	1	⁠2/3⁠	⁠1/2⁠	⁠2/7⁠		237–240		⁠52+1/2⁠	238.669725		63	238.480942392
tierce		6	3	2	⁠1+1/2⁠	1	⁠3/4⁠	⁠3/7⁠		158–160		35	159.11315		42	158.987294928
barrel		8	4	⁠2+2/3⁠	2	⁠1+1/3⁠	1	⁠4/7⁠		118–120		⁠26+1/4⁠	119.3348625		⁠31+1/2⁠	119.240471196
rundlet		14	7	⁠4+2/3⁠	⁠3+1/2⁠	⁠2+1/3⁠	⁠1+3/4⁠	1		68–69		15	68.19135		18	68.137412112

Definitions

In the US customary system, the tun (symbol: US tu^[7]) is defined as 252 US fluid gallons, or exactly 953.923769568 litres.^[7]

In the imperial system, the tun is defined as 210 imperial gallons, or exactly 954.6789 litres.

Conversions

Both the imperial and US tuns are subdivided into smaller units as follows.

1 tun	≡	2	butts or pipes
	≡	3	puncheons or tertians
	≡	4	wine hogsheads[7]
	≡	6	tierces
	≡	8	wine barrels
	≡	14	rundlets
Conversions of the imperial tun are as follows.
1 imperial tun	≡	210	imperial gallons
	≡	840	imperial quarts
	≡	1680	imperial pints
	≡	954.6789	litres[nb 9]
	≈	58258.0809	cubic inches
	≈	33.7142	cubic feet
	≈	1.2487	cubic yards
	≈	252.1995	US gallons
	≈	1008.7979	US liquid quarts
	≈	2017.5959	US liquid pints
	≈	866.9277	US dry quarts
	≈	1733.8553	US dry pints
Conversions of the US tun are as follows.
1 US tun	≡	252	US gallons[7]
	≡	1008	US liquid quarts[7]
	≡	2016	US liquid pints[7]
	≡	953.9237769568	litres[nb 10]
	≡	58212	cubic inches
	≡	33.6875	cubic feet
	≡	⁠1+107/432⁠	cubic yards
	≈	209.8339	imperial gallons
	≈	839.3356	imperial quarts
	≈	1678.6712	imperial pints
	≡	⁠866+26014/107521⁠	US dry quarts
	≡	⁠1732+52028/107521⁠	US dry pints

English wine cask units[8] gallon rundlet barrel tierce hogshead puncheon, tertian pipe, butt tun 1 tun 1 2 pipes, butts 1 1+1⁄2 3 puncheons, tertians 1 1+1⁄3 2 4 hogsheads 1 1+1⁄2 2 3 6 tierces 1 1+1⁄3 2 2+2⁄3 4 8 barrels 1 1+3⁄4 2+1⁄3 3+1⁄2 4+2⁄3 7 14 rundlets 1 18 31+1⁄2 42 63 84 126 252 gallons (wine) 3.785 68.14 119.24 158.99 238.48 317.97 476.96 953.92 litres 1 15 26+1⁄4 35 52+1⁄2 70 105 210 gallons (imperial) 4.546 68.19 119.3 159.1 238.7 318.2 477.3 954.7 litres

Explanatory notes

1. 256=2⁸
2. 252 = 2²×3²×7
3. The volume, V, of this cylinder may be approximated from the height, h, and the radius, r, as follows.

   V	= πr2h
   	≈ 22⁄7×(21 in)2×42 in	since π ≈ 22⁄7
   	= (22×32×7)×(3×7×11) cu in
   	= 252×231 cu in

4. 210 = 2×3×5×7
5. The imperial tun is only about 0.08% larger than the US tun under current definitions, as 5 imp gal ≈ 6 US gal.
6. The conversion to litres is approximate, and is given as a range to reflect the varying definitions of the gallon and the tun in terms of the gallon.
7. The conversion to litres shown in tooltips is exact assuming the current 4.54609-litre definition of the imperial gallon.
8. The conversion to litres shown in tooltips is exact assuming the current 25.4-millimetre definition of the international inch.
9. The conversion to litres is exact assuming the current 4.54609-litre definition of the imperial gallon.
10. The conversion to litres is exact assuming the current 25.4-millimetre definition of the international inch.

See also

• Tonelada