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English units of measurement

English units of measurement, principal system of weights and measures used in a few nations, the only major industrial one being the United States. It actually consists of two related systems—the U.S. Customary System of units, used in the United States and dependencies, and the British Imperial System. The names of the units and the relationships between them are generally the same in both systems, but the sizes of the units differ, sometimes considerably.

Customary Units of Weights and Measures

Units of Weight

The pound (lb) is the basic unit of weight (which is proportional to mass). Within the English units of measurement there are three different systems of weights. In the avoirdupois system, the most widely used of the three, the pound is divided into 16 ounces (oz) and the ounce into 16 drams. The ton, used to measure large masses, is equal to 2,000 lb (short ton) or 2,240 lb (long ton). In Great Britain the stone, equal to 14 lb, is also used. The troy system (named for Troyes, France, where it is said to have originated) is used only for precious metals. The troy pound is divided into 12 ounces and the troy ounce into 20 pennyweights or 480 grains; the troy pound is thus 5,760 grains. The grain is also a unit in the avoirdupois system, 1 avoirdupois pound being 7,000 grains, so that the troy pound is 5,760/7,000 of an avoirdupois pound. Apothecaries' weights are based on troy weights; in addition to the pound, ounce, and grain, which are equal to the troy units of the same name, other units are the dram (1/8 oz) and the scruple (1/24 oz or 1/3 dram).

Units of Length and Area

The basic unit of length is the yard (yd); fractions of the yard are the inch (1/36 yd) and the foot (1/3 yd), and commonly used multiples are the rod (51-2 yd), the furlong (220 yd), and the mile (1,760 yd). The acre, equal to 4,840 square yards or 160 square rods, is used for measuring land area.

Units of Liquid Measure

For liquid measure, or liquid capacity, the basic unit is the gallon, which is divided into 4 quarts, 8 pints, or 32 gills. The U.S. gallon, or wine gallon, is 231 cubic inches (cu in.); the British imperial gallon is the volume of 10 lb of pure water at 62℉ and is equal to 277.42 cu in. The British units of liquid capacity are thus about 20% larger than the corresponding American units. The U.S. fluid ounce is 1/16 of a U.S. pint; the British unit of the same name is 1/20 of an imperial pint and is thus slightly smaller than the U.S. fluid ounce.

Units of Dry Measure

For dry measure, or dry capacity, the basic unit is the bushel, which is divided into 4 pecks, 32 dry quarts, or 64 dry pints. The U.S. bushel, or Winchester bushel, is 2,150.42 cu in. and is about 3% smaller than the British imperial bushel of 2,219.36 cu in., with a similar difference existing between U.S. and British subdivisions. The barrel is a unit for measuring the capacity of larger quantities and has various legal definitions depending on the quantity being measured, the most common value being 105 dry quarts.

Differences between American and British Systems

Many American units of weights and measures are based on units in use in Great Britain before 1824, when the British Imperial System was established. Since the Mendenhall Order of 1893, the U.S. yard and pound and all other units derived from them have been defined in terms of the metric units of length and mass, the meter and the kilogram; thus, there was no longer any direct relationship between American units and British units of the same name. In 1959 an international agreement was reached among English-speaking nations to use the same metric equivalents for the yard and pound for purposes of science and technology; these values are 1 yd=0.9144 meter (m) and 1 lb=0.45359237 kilogram (kg). In the United States, the older definition of the yard as 3,600/3,937 m has continued to be used in many instances for surveying, the corresponding foot (1,200/3,937 m) being known as the survey foot; the survey foot will become obsolete in 2023.

The English units of measurement have many drawbacks: the complexity of converting from one unit to another, the differences between American and British units, the use of the same name for different units (e.g., ounce for both weight and liquid capacity, quart and pint for both liquid and dry capacity), and the existence of three different systems of weights (avoirdupois, troy, and apothecaries'). Because of these disadvantages and because of the wide use of the much simpler metric system in most other parts of the world, there have been proposals to do away with the U.S. Customary System and replace it with the metric system.


See L. J. Chisholm, Units of Weights and Measure: International and U.S. Customary (U.S. National Bureau of Standards, 1967).

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Abbreviated bu.
A unit of volume (dry measure) used in the United States, equal to 2150.42 cubic inches or approximately 35.239 liters.
A unit of volume (liquid and dry measure) used in Britain, equal to 2219.36 cubic inches or 8 imperial gallons (approximately 36.369 liters).
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


1. a Brit unit of dry or liquid measure equal to 8 Imperial gallons. 1 Imperial bushel is equivalent to 0.036 37 cubic metres
2. a US unit of dry measure equal to 64 US pints. 1 US bushel is equivalent to 0.035 24 cubic metres
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
The south-north length of 2,250 bu can be divided into reasonable segments: 450 bu + 50 bu + 450 bu + 100 bu + 550 bu + 50 bu + 550 bu + 50 bu.
The size of the bo adjoining the Inner Palace is 450 bu x 700 bu and that of the bo adjoining the Imperial Court is 550 bu x 700 bu.
The width of all south-north streets is set at a measure that is a half the width of the trunk street, which is 50 bu. The east-west lengths of the large blocks just below the Imperial Court are divided into four bo: 100 bu + 475 bu + 50 bu + 375 bu + 100 bu + 375 bu + 50 bu + 475 bu + 100 bu.
The second observation is that sentences containing the aspectual marker zhe are not always incompatible with bu. Illustrated below are two examples in which bu cooccurs with zhe.
If Bertinetto's distinction between attitudinals and pure habituals is correct, an interesting prediction by the aspectual constraint on bu is that only attitudinals but not pure habituals may be negated by bu. Is this prediction borne out?
This then predicts that the negation marker in this type of sentence should be mei rather than bu. Very interestingly, both bu and mei may occur in habitual sentences.
This is the first large case-control study to describe sociodemographic and environmental factors associated with BU. Our data show that BU was associated with age, place of residence, and water sources for all persons, and that BU was associated with a BCG scar in persons [greater than or equal to] 5 years old.
Children 3-4 years old had an increased risk for BU if they used unprotected water and lived in areas endemic for BU. That clothing provides protection against BU has already been reported in Cote d'Ivoire (3).
Children 5-14 years old and persons >49 years old were at higher risk for BU. Their attire and contact with environmental sources of M.
As seen from the above representation, perfective -le occurs in the restrictor and thus takes a narrow scope with respect to bu. Its event-based representation is given below.
This raises a question of binding focused elements to the left of bu. We think it is the other focus-sensitive operators, not bu, that associate with them.