English units

This article is about the historical development of measurement in England up to 1824. For the non-metric measurement system used in the UK, see Imperial units. For the system currently used in the US with similar unit names, see United States customary units. For an overview of both UK and US non-metric units, see Imperial and US customary measurement systems.

English units are the historical units of measurement used in England up to 1824, which evolved as a combination of the Anglo-Saxon and Roman systems of units. Various standards have applied to English units at different times, in different places, and for different applications. The units were redefined in the United Kingdom in 1824 by a Weights and Measures Act, which retained many but not all of the unit names and redefined some of the definitions.

The term "English units" is ambiguous, as it could refer either to the imperial units used in the UK, or to United States customary units, which retains some unit names but has some different definitions. (The terms imperial units or imperial measurements are used in the UK to refer to the non-metric system since they were used as a standard throughout the British Empire and the Commonwealth.)

History

Very little is known of the measurement units of the British Isles prior to Roman colonization in the 1st century AD. During the Roman period, Roman Britain relied on Ancient Roman units of measurement. During the Anglo-Saxon period, the North German foot of 335 millimetres (13.2 inches) was the nominal basis for other units of linear measurement. The foot was divided into 4 palms or 12 thumbs. A cubit was 2 feet, an elne 4 feet. The rod was 15 Anglo-Saxon feet, the furlong 10 rods. An acre was 4 × 40 rods, i.e., 160 square rods or 36,000 square Anglo-Saxon feet. However, Roman units continued to be used in the construction crafts and reckoning by the Roman mile of 5000 feet or 8 stades continued, in contrast to other Germanic countries who adopted the name "mile" for a longer native length closer to the league. From the time of Offa King of Mercia (8th century) until 1526 the Saxon pound, also known as the moneyers' pound (and later known as the Tower pound) was the fundamental unit of mass measurement.

Prior to the enactment of a law known as the "Composition of Yards and Perches" (Latin: Compositio ulnarum et perticarum) some time between 1266 and 1303, the English system of measurement had been based on that of the Anglo-Saxons, inherited from tribes from northern Germany. The Compositio retained the Anglo-Saxon rod of 5.03 metres and the acre of 4 × 40 rods. However, it redefined the yard, foot, inch, and barleycorn to ​¹⁰⁄₁₁ of their previous value. Thus, the rod went from 5 old yards to ​5 ¹⁄₂ new yards, or 15 old feet to ​16 ¹⁄₂ new feet. The furlong went from 600 old feet (200 old yards) to 660 new feet (220 new yards). The acre went from 36,000 old square feet to 43,560 new square feet. Scholars have speculated that the Compositio may have represented a compromise between two earlier systems of the units, the Anglo-Saxon and the Roman.

Contrary to popular belief, the Norman conquest of England had little effect on British weights and measures other than to introduce one new unit: the bushel. William the Conqueror, in one of his first legislative acts, confirmed existing Anglo-Saxon measurement, a position which was consistent with Norman policy in dealing with occupied peoples. Another popular myth is that the Magna Carta of 1215 (specifically chapter 35) had any significant effect on English weights and measures, as this document only mentions one unit (the London Quarter) but does not define it.

Later development of the English system continued by defining the units by law and issuing measurement standards. Standards were renewed in 1496, 1588 and 1758. The last Imperial Standard Yard in bronze was made in 1845; it served as the standard in the United Kingdom until the yard was redefined by the international yard and pound agreement as 0.9144 metre in 1959 (statutory implementation: Weights and Measures Act of 1963). The English system then spread to other parts of the British Empire.

Length

Chart showing the relationships of distance measures.

Poppyseed 

​¹⁄₄ or ​¹⁄₅ of a barleycorn

Line 

​¹⁄₄ of a barleycorn

Barleycorn 

​¹⁄₃ of an inch, the notional base unit under the Composition of Yards and Perches.

Digit 

​³⁄₄ inch

Finger 

​⁷⁄₈ inch

Hand 

4 inches

Inch 

legally, 3 barleycorns.

Nail 

3 digits = ​2 ¹⁄₄ inches = ​¹⁄₁₆ yard

Palm 

3 inches

Shaftment 

Width of the hand and outstretched thumb, ​6 ¹⁄₂ inches before 1066, 6 thereafter

Link 

7.92 inches or one 100th of a chain.

Span 

Width of the outstretched hand, from the tip of the thumb to the tip of the little finger, 3 palms = 9 inches

Foot 

Prior to the Anglo-Saxon invasions, the Roman foot of 11.65 inches (296 mm) was used. The Anglo-Saxons introduced a North-German foot of 13.2 inches (335 mm), divided into 4 palms or 12 thumbs, while the Roman foot continued to be used in the construction crafts. In the late 13th century, the modern foot of 304.8 mm was introduced, equal to exactly ​¹⁰⁄₁₁ Anglo-Saxon foot.

Cubit 

From fingertips to elbow, 18 inches.

Yard (= Ulna) 

3 feet = 36 inches, the practical base unit as the length of the prototype bar held by the Crown or Exchequer.

Ell 

From fingertip of outstretched arm to opposite shoulder, 20 nails = ​1 ¹⁄₄ yard or 45 inches. Mostly for measuring cloth

Fathom 

Distance fingertip to fingertip arms outstretched, 6 feet

Rod (= perch) (= pole)

Used for surveying land and in architecture. The rod is the same length today as in Anglo-Saxon times, although its composition in terms of feet were changed by the Composition of Yards and Perches from 15 feet to ​16 ¹⁄₂. The pole is commonly used as a measurement for Allotment Gardens. (See also perch as an area and a volume unit.)

Chain 

four linear rods. Named after the length of surveyor's chain used to measure distances until quite recently. Any of several actual chains used for land surveying and divided in links. Gunter's chain, introduced in the 17th century, is 66 feet.

Furlong (= stade) 

Notionally the distance a plow team could furrow without rest, but actually a measure of 40 rods or 600 feet prior to the Composition of Yards and Perches and 40 rods or 660 feet afterwards.

Mile 

Originally the Roman mile alternately reckoned as 5000 feet, 1000 paces, or 8 stades but adjusted to 5280 feet in 1593 to account for the differences introduced to these methods of reckoning by the Composition of Yards and Perches.

League 

Notionally an hour's travel, but usually reckoned as three miles. Approximate length of the traditional "mile" in German and Scandinavian countries.

Area

Acre

area of land one chain (four rods) in width by one furlong in length. As the traditional furlong could vary in length from country to country, so did the acre. In England an acre was 4,840 square yards, in Scotland 6,150 square yards and in Ireland 7,840 square yards. It is a Saxon unit, meaning field. Traditionally said to be "as much area as could be ploughed in one day".

Rood

one quarter of an acre, confusingly sometimes called an acre itself in many ancient contexts. One furlong in length by one rod in width, or 40 square rods.

Carucate

an area equal to that which can be ploughed by one eight-oxen team in a single year (also called a plough or carve). Approximately 120 acres.

Bovate

the amount of land one ox can plough in a single year (also called an oxgang). Approximately 15 acres or one eighth of a carucate.

Perch

an area equal to one square rod. (See also perch as a length and volume unit.)

Virgate

the amount of land a pair of oxen can plough in a single year. Approximately 30 acres (also called yard land).

Administrative units

Hide

four to eight bovates. A unit of yield, rather than area, it measured the amount of land able to support a single household for agricultural and taxation purposes.

Knight's fee

five hides. A knight's fee was expected to produce one fully equipped soldier for a knight's retinue in times of war.

Hundred or wapentake

100 hides grouped for administrative purposes.

Volume

General

Chart showing the relationships of volume measures.

Dram

60 minim or drops or ​¹⁄₈ fluid ounce (fl oz)

Teaspoon

80 minim or drops or ​¹⁄₆ fl oz

Tablespoon or mouthful

4 dram, 3 teaspoons or ​¹⁄₂ fl oz

Pony

6 dram or ​³⁄₄ fl oz

Jigger

3 tablespoons, 2 pony or 1.5 fl oz

Jack or jackpot

5 tablespoons or 2.5 fl oz (double this for milk and beer in Northern England)

Gill

2 jack or 5 fl oz (or double this for milk and beer in Northern England)

Cup

2 gill or 10 fl oz

Pint

2 cup or 20 fl oz ("A pint of pure water weighs a pound and a quarter")

Quart

2 pint, 40 fl oz or ​¹⁄₄ gallon

Pottle

2 quart, 80 fl. oz or ​¹⁄₂ gallon

Gallon

2 pottle, 4 quarts, 8 pints or 160 fl oz

Dry goods

Dry gallon

4 dry quarts or 8 dry pints

Peck

2 dry gallons

Kenning

2 peck or 4 dry gallons

Bushel

2 kenning, 4 pecks or 8 dry gallons

Strike

2 bushels or 16 dry gallons

Coomb or dry barrel

2 strike, 4 bushels or 32 dry gallons

Dry hogshead

2 Coomb, 64 dry gallons or ​¹⁄₄ dry tun

	tablespoon	pony	jack	gill	cup	pint	quart	pottle	gallon	peck	kenning	bushel	strike	coomb	hogshead	butt/pipe	2n gal.
1 tablespoon =	1	​1⁄2	​1⁄4	​1⁄8	​1⁄16	​1⁄32	​1⁄64	​1⁄128	​1⁄256	​1⁄512	​1⁄1024	​1⁄2048	​1⁄4096	​1⁄8192	​1⁄16384	​1⁄32768	–8
1 pony =	2	1	​1⁄2	​1⁄4	​1⁄8	​1⁄16	​1⁄32	​1⁄64	​1⁄128	​1⁄256	​1⁄512	​1⁄1024	​1⁄2048	​1⁄4096	​1⁄8192	​1⁄16384	–7
1 jack =	4	2	1	​1⁄2	​1⁄4	​1⁄8	​1⁄16	​1⁄32	​1⁄64	​1⁄128	​1⁄256	​1⁄512	​1⁄1024	​1⁄2048	​1⁄4096	​1⁄8192	–6
1 gill =	8	4	2	1	​1⁄2	​1⁄4	​1⁄8	​1⁄16	​1⁄32	​1⁄64	​1⁄128	​1⁄256	​1⁄512	​1⁄1024	​1⁄2048	​1⁄4096	–5
1 cup =	16	8	4	2	1	​1⁄2	​1⁄4	​1⁄8	​1⁄16	​1⁄32	​1⁄64	​1⁄128	​1⁄256	​1⁄512	​1⁄1024	​1⁄2048	–4
1 pint =	32	16	8	4	2	1	​1⁄2	​1⁄4	​1⁄8	​1⁄16	​1⁄32	​1⁄64	​1⁄128	​1⁄256	​1⁄512	​1⁄1024	–3
1 quart =	64	32	16	8	4	2	1	​1⁄2	​1⁄4	​1⁄8	​1⁄16	​1⁄32	​1⁄64	​1⁄128	​1⁄256	​1⁄512	–2
1 pottle =	128	64	32	16	8	4	2	1	​1⁄2	​1⁄4	​1⁄8	​1⁄16	​1⁄32	​1⁄64	​1⁄128	​1⁄256	–1
1 gallon =	256	128	64	32	16	8	4	2	1	​1⁄2	​1⁄4	​1⁄8	​1⁄16	​1⁄32	​1⁄64	​1⁄128	0
1 peck =	512	256	128	64	32	16	8	4	2	1	​1⁄2	​1⁄4	​1⁄8	​1⁄16	​1⁄32	​1⁄64	1
1 kenning =	1,024	512	256	128	64	32	16	8	4	2	1	​1⁄2	​1⁄4	​1⁄8	​1⁄16	​1⁄32	2
1 bushel =	2,048	1,024	512	256	128	64	32	16	8	4	2	1	​1⁄2	​1⁄4	​1⁄8	​1⁄16	3
1 strike =	4,096	2,048	1,024	512	256	128	64	32	16	8	4	2	1	​1⁄2	​1⁄4	​1⁄8	4
1 coomb =	8,192	4,096	2,048	1,024	512	256	128	64	32	16	8	4	2	1	​1⁄2	​1⁄4	5
1 hogshead =	16,384	8,192	4,096	2,048	1,024	512	256	128	64	32	16	8	4	2	1	​1⁄2	6
1 butt/pipe =	32,768	16,384	8,192	4,096	2,048	1,024	512	256	128	64	32	16	8	4	2	1	7

Specific goods

Oil barrel

35 gallons (or 42 wine gallons)

Perch

24.75 cubic feet of dry stone, derived from the more commonly known perch, a unit of length equal to 16.5 feet.

Cord

128 cubic feet of firewood, a stack of firewood 4 ft × 4 ft × 8 ft

Ale, beer and liquids

Pin

4.5 gallons or ​¹⁄₈ beer barrel

Firkin

2 pins, 9 gallons (ale, beer or goods) or ​¹⁄₄ beer barrel

Kilderkin

2 firkins, 18 gallons or ​¹⁄₂ beer barrel

Beer barrel

2 kilderkins, 36 gallons or ​²⁄₃ beer hogshead

Beer hogshead

3 kilderkins, 54 gallons or 1.5 beer barrels

Beer pipe or butt

2 beer hogsheads, 3 beer barrels or 108 gallons

Beer tun

2 beer pipes or 216 gallons

English brewery cask units

gallon	firkin	kilderkin	barrel	hogshead		Year designated
				1	hogsheads
			1	​1 1⁄2	barrels
		1	2	3	kilderkins
	1	2	4	6	firkins
1	8	16	32	48	ale gallons	(1454)
= 4.621 l	= 36.97 l	= 73.94 l	= 147.9 l	= 221.8 l
1	9	18	36	54	beer gallons
= 4.621 l	= 41.59 l	= 83.18 l	= 166.4 l	= 249.5 l
1	​8 1⁄2	17	34	51	ale gallons	1688
= 4.621 l	= 39.28 l	= 78.56 l	= 157.1 l	= 235.7 l
1	9	18	36	54	ale gallons	1803
= 4.621 l	= 41.59 l	= 83.18 l	= 166.4 l	= 249.5 l
1	9	18	36	54	imperial gallons	1824
= 4.546 l	= 40.91 l	= 81.83 l	= 163.7 l	= 245.5 l

Wine

Wine is traditionally measured based on the wine gallon, which was reëstablished by Queen Anne in 1707 after a 1688 survey found the Exchequer no longer possessed the necessary standard but had instead been depending on a copy held by the Guildhall. Defined as 231 cubic inches, it differs from the later imperial gallon, but is equal to the United States customary gallon.

Rundlet

18 wine gallons or ​¹⁄₇ wine pipe

Wine barrel

31.5 wine gallons or ​¹⁄₂ wine hogshead

Tierce

42 wine gallons, ​¹⁄₂ puncheon or ​¹⁄₃ wine pipe

Wine hogshead

2 wine barrels, 63 wine gallons or ​¹⁄₄ wine tun

Puncheon or tertian

2 tierce, 84 wine gallons or ​¹⁄₃ wine tun

Wine pipe or butt

2 wine hogshead, 3 tierce, 7 roundlet or 126 wine gallons

Wine tun

2 wine pipe, 3 puncheon or 252 wine gallons

English wine cask units

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

Weight

Chart showing the relationships of weight measures.

The Avoirdupois, Troy and Apothecary systems of weights all shared the same finest unit, the grain; however, they differ as to the number of grains there are in a dram, ounce and pound. This grain was legally defined as the weight of a grain seed from the middle of an ear of barley. There also was a smaller wheat grain, said to be ​³⁄₄ (barley) grains or about 48.6 milligrams.

Avoirdupois

Main article: Avoirdupois

Grain (gr) 

64.79891 mg, ​¹⁄₇₀₀₀ of a pound

Dram/drachm (dr) 

27.34375 gr (sixteenth of an ounce) (possibly originated as the weight of silver in Ancient Greek coin drachma)

Ounce (oz) 

16 dr = 437.5 grains ≈ 28 g

Pound (lb) 

16 oz = 7000 grains ≈ 454 g (NB: 'lb' stands for libra)

Quarter 

​¹⁄₄ cwt

Hundredweight (cwt) 

112 lb

Ton 

20 cwt

Additions:

Nail 

​¹⁄₁₆ cwt = 7 lb

Clove 

7 lb (wool) or 8 lb (cheese)

Stone (st) 

14 lb (see Stone (unit) for other values)

Tod 

2 st = ​¹⁄₄ cwt (long)

Troy and Tower

The Troy and Tower pounds and their subdivisions were used for coins and precious metals. The Tower pound, which was based upon an earlier Anglo-Saxon pound, was replaced by the Troy pound when a proclamation dated 1526 required the Troy pound to be used for mint purposes instead of the Tower pound. No standards of the Tower pound are known to have survived.

In terms of nominal currency units, a pound was 20 shillings of 12 pennies each (i.e. 240) from the late 8th century (Charlemagne/Offa of Mercia) to 1971 in the United Kingdom.

Troy

Main article: Troy weight

Grain (gr) 

= 64.79891 mg

Pennyweight (dwt) 

24 gr ≈ 1.56 g

Ounce (oz t) 

20 dwt = 480 gr ≈ 31.1 g

Pound (lb t) 

12 oz t = 5760 gr ≈ 373 g

Mark

8 oz t

Tower

Grain (gr) 

= ​⁴⁵⁄₆₄ gr t ≈ 45.6 mg

Pennyweight (dwt) 

32 gr T = ​22 ¹⁄₂ gr t ≈ 1.46 g

Tower ounce 

20 dwt T = 640 gr T = ​18 ³⁄₄ dwt t = 450 gr t ≈ 29.2 g

Tower pound 

12 oz T = 240 dwt T = 7680 gr T = 225 dwt t = 5400 gr t ≈ 350 g

Mark

8 oz T ≈ 233 g

Apothecary

Main article: Apothecaries' system

Grain (gr) 

= 64.79891 mg

Scruple (s ap) 

20 gr

Dram (dr ap) 

3 s ap = 60 gr

Ounce (oz ap) 

8 dr ap = 480 gr

Pound (lb ap) 

5760 gr = 1 lb t

Others

Merchants/Mercantile pound 

15 oz tower = 6750 gr ≈ 437.4 g

London/Mercantile pound 

15 oz troy = 16 oz tower = 7200 gr ≈ 466.6 g

Mercantile stone 

12 lb L ≈ 5.6 kg

Butcher's stone 

8 lb ≈ 3.63 kg

Sack 

26 st = 364 lb ≈ 165 kg

The carat was once specified as four grains in the English-speaking world.

Some local units in the English dominion were (re-)defined in simple terms of English units, such as the Indian tola of 180 grains.

Tod

This was a English weight for wool. It has the alternate spelling forms of tode, todd, todde, toad, and tood. It was usually 28 pounds, or two stone. The tod, however, was not a national standard and could vary by English shire, ranging from 28 to 32 pounds. In addition to the traditional definition in terms of pounds, the tod has historically also been considered to be ​¹⁄₁₃ of a sack, ​¹⁄₂₆ of a sarpler, or ​¹⁄₉ of a wey.

English pounds

Unit	Pounds											Ounces						Grains		Metric
	Avdp.		Troy		Tower		Merchant		London		Metric	Avdp.		Troy		Tower		Troy	Tower	g	kg
Avoirdupois	1		175/144	= 1.21527	35/27	= 1.296	28/27	= 1.037	35/36	= 0.972	≈ 0.9072	16		14+7/12	= 14.583	15+5/9	= 15.5	7000	09955+5/9	≈ 454	≈ 5/11
Troy	144/175	≈ 0.8229	1		16/15	= 1.06	64/75	= 0.853	4/5	= 0.8	≈ 0.7465	13+29/175	≈ 13.17	12		12+4/5	= 12.8	5760	08192	≈ 373	≈ 3/8
Tower	27/35	≈ 0.7714	15/16	= 0.9375	1		4/5	= 0.8	3/4	= 0.75	≈ 0.6998	12+12/35	≈ 12.34	11+1/4	= 11.25	12		5400	07680	≈ 350	≈ 7/20
Merchant	27/28	≈ 0.9643	75/64	= 1.171875	5/4	= 1.25	1		15/16	= 0.9375	≈ 0.8748	15+3/7	≈ 15.43	14+1/16	= 14.0625	15		6750	09600	≈ 437	≈ 7/16
London	36/35	≈ 1.029	5/4	= 1.25	4/3	= 1.3	16/15	= 1.06	1		≈ 0.9331	16+16/35	≈ 16.46	15		16		7200	10240	≈ 467	≈ 7/15
Metric		≈ 1.1023		≈ 1.3396		≈ 1.4290		≈ 1.1431		≈ 1.0717	1		≈ 17.64		≈ 16.08		≈ 17.15	7716	10974	= 500	= 1/2

See also

• Approximate conversion of units
• Comparison of the imperial and US customary measurement systems
• Domesday Book
• English Engineering Units
• Feudalism
• History of measurement
• Hundred, a unit of 100, 120, &c. items
• Imperial and US customary measurement systems
• Imperial units

• Long hundred of 120
• Metrication
• Obsolete Scottish units of measurement
• Plan for Establishing Uniformity in the Coinage, Weights, and Measures of the United States
• Slug and poundal
• Spanish customary units
• Weights and measures
• Welsh units
• Winchester measure

External links

• English Customary Weights and Measures
• Jacques J. Proot's Anglo-Saxon weights & measures page. Internet Archive Wayback Machine
• Alexander Justice, "A General Discourse of the Weights and Measures" (London, 1707).