English units

History

Very little is known of the measurement units of the British Isles prior to Roman colonization in the 1st century CE. 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.

Timeline

Selected excerpts from the bibliography of Marks and Marking of Weights and Measures of the British Isles

1215 Magna Carta: the earliest statutory declaration for uniformity of weights and measures

1335: 8 & 9 Edw III c1 First statutory reference describing goods as avoirdupois

1414 2 Hen V c4 First statutory mention of the Troy pound

1495 12 Hen VII c5 New Exchequer standards were constructed including Winchester capacity measures defined by Troy weight of their content of threshed wheat by stricken measure (first statutory mention of Troy weight as standard weight for bullion, bread, spices &c).

1527 Hen VIII Abolished the Tower pound

1531 23 Hen VIII c4 Barrel to contain 36 gallons of beer or 32 of ale; kilderkin in half of this; firkin half again

1532 24 Hen VIII c3 First statutory references to use of avoirdupoi weight

1536 28 Hen VIII c4 Added the tierce (41 gallons)

1588 (Elizabeth I) A new series of Avoirdupois standard bronze weights (bell-shaped from 56lbs to 2lb and flat-pile from 8lbs to a dram) with new Troy standard weights in nested cups from 256 ozs to 1/8 oz in a binary progression.

1601–1602 Standard bushels and gallons were constructed based on the standards of Henry VII and a new series of capacity measures were issued.

1660 12 Chas II c24 Barrel of beer to be 36 gallons taken by the gauge of the Exchequer standar of the ale quart; barrel of ale to be 32 gallons; all other liquors retailed to be sold by the wine gallon;

1869 1 Wm & Mary c24 Barrels of beer and ale outside London to contain 34 gallons

1695 7 Will III c24 Irish Act about grain measures decreed: unit of measure to be Henry VIII's gallon as confirmed by Elizabeth I; i.e.e 272 1/4 cubic inches; standard measures of the barrel (32 gallons), half-barrel (16), bushel (8), peck (2) and gallon to be lodged in the Irish Exchequer; and copies were to be provided in every county, city, town, &c.

1696 8 & 9 Will III c22 Size of Winchester bushel "every round bushel with a plain and even bottom being 18 1/2" wide throughout and 8" deep" (i.e. a dry measure of 268.8 in³ per gallon).

1706 5 & 6 Anne c27 Wine gallon to be a cylindrical vessel with an even bottom 7" diameter throughout and 6" deep from top to bottom of the inside, or holding 231 in³ and no more.

1706 6 Anne c11 Act of Union decreed: the weights and measures of England to be those of Scotland whose burgs were to take charge of the duplicates of the English Standards sent to them.

1713 12 Anne c17 The legal coal bushel to be round with a plain and even bottom, 19 1/2" from outside to outside and to hold 1 Winchester bushel and 1 quart of water.

1718 5 Geo I c18 Decreed Scots Pint exactly 103 in³.

1803 43 Geo III c151 Referred to wine bottles making about 5 to the wine gallon (i.e. Reputed Quarts)

1824 5 Geo IV c74 Weights and Measures Act: completely reorganized British metrology and established Imperial weights and measures; defined the yard, troy and avoirdupois pounds and the gallon (as the standard measure for liquids and dry goods not measured by heaped measure), and provided for a 'brass' standard gallon to be constructed.

1825 6 Geo IV c12 Delayed introduction of Imperial weights and measures from 1 May 1825 to 1 January 1826.

1835 Will IV c63 Weights and measures act: abolished local and customary measures including the Winchester bushel; made heaped measure illegal; required trade to be carried out by avoirdupois weight only except for bullion; gems and drugs which were to be sold by troy weight; decreed that all forms of coal were to be sold by weight and not measure; legalised the 14 lb stone, the 112 lb hundredweight and the 20 cwt ton.

1853 16 & 17 Vict c29 Permitted the use of decimal Bullion weights.

1866 29 & 30 Vict c82 Standards of Weights, Measures and Coinage Act: transferred all duties and standards from the Exchequer to the newly created Standards Department of the Board of Trade.

1878 41 & 42 Vict c49 Weights and Measures Act: defined the Imperial standard yard and pound; enumerataed the secondary standards of measure and weight derived from the Imperial standards; required all trade by weight or measure to be in terms of one of the Imperial weights or measures or some multiple part thereof; abolished the Tory pound.

1963 11 & 12 Eliz II c31 Weights and Measures Act: abolished the chaldron of coal, the fluid drachm and minim (effective 1.2.1971), discontinued the use of the quarter, abolished the use of the bushel and peck and abolished the pennyweight (from 31.1.1969).

Length

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 

3 barleycorns (the historical legal definition)

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 alternatively 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.

General

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

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

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

Weight

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.

The avoirdupois pound contained 7,000 grains and was used for all products not subject to Apothecaries's or Tower weight.

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

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

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 alternative 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.