# gallon

The gallon ( English gallon ) is a unit of space (liquid and dry measure ) of the Anglo-American system of measurement .

The unit symbol is depending on the exact volume definition Imp.gal., US.liq.gal. or US.dry.gal.

## Volume measurements

### Imperial system of measurement

Physical unit
Unit name Imperial gallon
Unit symbol ${\ displaystyle \ mathrm {Imp.gal}}$ Physical quantity (s) volume
Formula symbol ${\ displaystyle V}$ dimension ${\ displaystyle {\ mathsf {L ^ {3}}}}$ system Anglo-American system of measurement
In SI units ${\ displaystyle \ mathrm {1 \, Imp.gal = 4 {,} 546 \, 09 \ cdot 10 ^ {- 3} \; m ^ {3}}}$ Named after english gallon

1 Imp.gal. = 4  Imp.qt. = 8  imp.pt. = 16  Imp.cup = 32  Imp.gi. = 160  Imp.fl.oz. = 4.54609  liters (exactly by definition)568.261.2502.048.383  inch³ ≈ 277.41945  inch³

1 Imp.gal. = 568,261,250473,176,473 US.liq.gal. ≈ 1.20095 US.liq.gal.

The British (Imperial) gallon is based on a medieval English beer measure. In 1824 it was redefined on a physical basis as the volume of 10 pounds of distilled water at 62 ° F (17 ° C), measured with brass weights of a certain composition at a fixed air pressure, as well as the definition of 1 gallon = 277.42 cubic inches . In 1985, following the Canadian model, a redefinition based on the metric liter was introduced, whereby a gallon is now slightly less than 277.42 cubic inches. In the USA, on the other hand, a definition that comes from the wine trade is used.

### American system of measurement

Physical unit
Unit name US liquid gallon
Unit symbol ${\ displaystyle \ mathrm {US.liq.gal}}$ Physical quantity (s) volume
Formula symbol ${\ displaystyle V}$ dimension ${\ displaystyle {\ mathsf {L ^ {3}}}}$ system Anglo-American system of measurement
In SI units ${\ displaystyle \ mathrm {1 \, US.liq.gal = 3 {,} 785 \, 411 \, 784 \ cdot 10 ^ {- 3} \; m ^ {3}}}$ Named after english gallon

1 US.liq.gal. = 4  liquid qt. = 8  US.liq.pt. = 16  US.cup = 32  US.liq.gi. = 128  US.fl.oz. = 231 in³ = 3.785411784 liters

The US gallon is based on a medieval English Weinmaß, originally as a cylinder with a height of 6 inches (Engl. Inch ) was defined and a diameter of 7 inches. The circle number π was then usually approximated with 22/7. In 1706, during the reign of Queen Anne , the Weingallon was redefined as a cuboid with dimensions of 3 × 7 × 11 inch³, which corresponds to the old cylinder volume, calculated with the aforementioned approximation for π. This definition is still in use in the USA today, but in Great Britain itself it has been superseded by the Imperial Gallon, which originated in the beer trade. Since the inch is now defined as 1 inch = 25.4 mm as a decimal multiple of the meter, the volume of the US gallon can be specified exactly in liters.

Furthermore, 1 petroleum barrel = 42 US.liq.gal. = 9702  cubic inch = 158.987294928 liter

### Volume unit for dry goods

Physical unit
Unit name US dry gallon (corn gallon)
Unit symbol ${\ displaystyle \ mathrm {US.dry.gal}}$ Physical quantity (s) volume
Formula symbol ${\ displaystyle V}$ dimension ${\ displaystyle {\ mathsf {L ^ {3}}}}$ system Anglo-American system of measurement
In SI units ${\ displaystyle \ mathrm {1 \, US.dry.gal = 4 {,} 404 \, 883 \, 770 \, 86 \ cdot 10 ^ {- 3} \; m ^ {3}}}$ Named after english gallon

1 US.dry.gal. = 4  US.dry.qt = 8  US.dry.pt = 268.8025  inch³ = 4.40488377086 liter

1 US.dry.gal. =  107,52192,400 US liq.gal  . ≈ 1.1636 U.S. liq.gal.

1 US.bushel = 4  peck = 8 US.dry.gal. = 2150.42 inch³ ≈ 35.239 liters

As a dry measure for wheat, flour and other things, it is not a legal unit in the United States or the United Kingdom today, but it was still common in the 19th century.

## Word origin

English gallon comes from Old Norman (Old North French) galon, which in turn is of unclear (perhaps Celtic ) origin. In English, the measure of liquid is first attested in 1300 (in this specific case for beer), and as dry measure for the first time in 1684 (for wheat).

## literature

• Johann Samuel Traugott Gehler: Physical dictionary. Volume 6, E. B. Schwickert, Leipzig 1836, p. 1309.
• Johann Friedrich Krüger : Complete manual of the coins, measurements and weights of all countries in the world. Verlag Gottfried Basse, Quedlinburg / Leipzig 1830, p. 104.

## Individual evidence

1. a b The Oxford English Dictionary . 2nd Edition. Volume 6. Clarendon Press, Oxford 1989, p. 334.
2. ^ The Oxford Dictionary of English Etymology. Edited by C. T. Onions . Clarendon Press, Oxford 1966 (with numerous, partly corrected new editions), article gallon .