Pound (mass)

A pound troy weight.

The pound or pound-mass is a unit of mass used in the imperial, United States customary and other systems of measurement. Various definitions have been used; the most common today is the international avoirdupois pound, which is legally defined as exactly 0.45359237 kilograms, and which is divided into 16 avoirdupois ounces.[1] The international standard symbol for the avoirdupois pound is lb;[2] an alternative symbol is lbm[3] (for most pound definitions), # (chiefly in the U.S.), and [4] or ″̶[5] (specifically for the apothecaries' pound).

The unit is descended from the Roman libra (hence the abbreviation "lb"). The English word pound is cognate with, among others, German Pfund, Dutch pond, and Swedish pund. All ultimately derive from a borrowing into Proto-Germanic of the Latin expression lībra pondō ("a pound by weight"), in which the word pondō is the ablative case of the Latin noun pondus ("weight").[6]

Usage of the unqualified term pound reflects the historical conflation of mass and weight. This accounts for the modern distinguishing terms pound-mass and pound-force.

Current use

The United States and countries of the Commonwealth of Nations agreed upon common definitions for the pound and the yard. Since 1 July 1959, the international avoirdupois pound (symbol lb) has been defined as exactly 0.45359237 kg.[7][8]

In the United Kingdom, the use of the international pound was implemented in the Weights and Measures Act 1963.[9]

The yard or the metre shall be the unit of measurement of length and the pound or the kilogram shall be the unit of measurement of mass by reference to which any measurement involving a measurement of length or mass shall be made in the United Kingdom; and- (a) the yard shall be 0.9144 metre exactly; (b) the pound shall be 0.45359237 kilogram exactly.

— Weights and Measures Act, 1963, Section 1(1)

An avoirdupois pound is equal to 16 avoirdupois ounces and to exactly 7,000 grains. The conversion factor between the kilogram and the international pound was therefore chosen to be divisible by 7, and an (international) grain is thus equal to exactly 64.79891 milligrams.

In the UK, the process of metrication and European units of measurement directives were expected to eliminate the use of the pound and ounce, but in 2007 the European Commission abandoned the requirement for metric-only labelling on packaged goods there, and allowed for dual metric–imperial marking to continue indefinitely.[10][11] When used as a measurement of body weight the UK practice remains to use the stone of 14 pounds as the primary measure e.g. "11 stone 4 pounds", rather than "158 pounds" (as done in the US),[12] or "72 kilograms" as used elsewhere.

The US has not adopted the metric system[13] despite many efforts to do so, and the pound remains widely used as one of the key United States customary units.

Other Languages
Afrikaans: Pond (eenheid)
العربية: رطل
български: Фунт
Boarisch: Pfund
bosanski: Funta
Чӑвашла: Кĕренке
Deutsch: Pfund
Ελληνικά: Λίβρα
Esperanto: Funto
føroyskt: Pund (vekteind)
galego: Libra (masa)
հայերեն: Ֆունտ
hrvatski: Funta
Bahasa Indonesia: Pon (satuan)
italiano: Libbra
עברית: ליברה
Kiswahili: Ratili
Kreyòl ayisyen: Liv (mezi)
Lëtzebuergesch: Pond
lietuvių: Svaras
македонски: Фунта (единица)
Bahasa Melayu: Paun (jisim)
Nederlands: Pond (massa)
Nordfriisk: Pünj
norsk nynorsk: Pund
occitan: Liura (pes)
oʻzbekcha/ўзбекча: Funt
Patois: Pong
Piemontèis: Lira
Plattdüütsch: Pund
polski: Funt (masa)
português: Libra (massa)
Ripoarisch: Pongk
română: Livră
саха тыла: Муунта
Scots: Pund
Simple English: Pound (mass)
slovenčina: Libra (hmotnosť)
slovenščina: Funt (mera)
српски / srpski: Фунта (маса)
srpskohrvatski / српскохрватски: Funta (masa)
suomi: Pauna
தமிழ்: இறாத்தல்
اردو: رطل
Tiếng Việt: Pound (khối lượng)
Winaray: Libra
ייִדיש: פונט