Stone (mass)

The stone is a unit of weight. It is part of the Imperial system of weights and measures used in the British Isles, and formerly used in most Commonwealth countries. It is equal to 16 pounds and approximately 62.3 Newtons, which is equivalent to about 6.35 kilograms (a unit of mass, not weight).

Eight stone make a hundredweight in the Imperial system.

When used as the unit of measurement, the plural form of "stone" is correctly "stone" (as in, "11 stone"), though "stones" is sometimes used, not usually by natives of the British Isles. The abbreviation is "st." When describing the units, the correct plural is "stones" (as in, "please enter your weight in stones and pounds").

History

The stone was historically used for weighing agricultural commodities. Potatoes, for example, were traditionally sold in stone and half-stone (14-pound and 7-pound) quantities.Historically the number of pounds in a stone varied by commodity, and was not the same in all times and places even for one commodity.The "OED" contains examples [http://dictionary.oed.com/cgi/entry/50238294 OED Definition for Stone - meaning 14a] ] including:Another example is the definition of the "stone" in the 1772 edition of Encyclopaedia Britannica [Encyclopaedia Britannica Vol III, Edinburgh - 1772] which reads "STONE also denotes a certain quantity or weight of some commodities. A stone of beef , at London, is the quantity of eight pounds; in Hertfordshire, twelve pounds; in Scotland sixteen pounds."

Current use

Although the 1985 Weights and Measures Act [1985 Weights and Measures Act [http://www.statutelaw.gov.uk/legResults.aspx?LegType=All+Legislation&title=Weights+and+Measures+Act&searchEnacted=0&extentMatchOnly=0&confersPower=0&blanketAmendment=0&NavFrom=0&activeTextDocId=2191980&PageNumber=1&SortAlpha=0] ] expressly prohibited the use of the stone as a unit of measure for purposes of trade (other than as a supplementary unit), the stone remains widely used within the British Isles as a means of expressing human body weight. People in these countries normally describe themselves as weighing, for example, "11 stone 4" (11 stone and 4 pounds), rather than "72 kilograms" in most other countries, or "158 pounds" (the conventional way of expressing the same weight in the United States). Its widespread colloquial use may be compared to the persistence in the British Isles of other Imperial units like the foot, the inch, and the mile, despite these having been supplanted entirely or partly by metric units in official use and other contexts. Road distances and speed enforcement area are still expressed officially in yards, miles and miles-per-hour in the United Kingdom. Both Canada and the Republic of Ireland now use the metric system. In official use, provision is usually made for the public to express body weight in either stones or kilograms (similar allowance is made for measuring height in feet and inches). For example, on a National Health Service website both metric and Imperial units are used [http://www.nhsdirect.nhs.uk/magazine/interactive/calories/index.aspx NHS Online Calorie Counter] ] .

Outside the British Isles, stone may also be used to express body weight in casual contexts in other Commonwealth countries.

See also

* Human weight
* Body weight
* Conversion of units
* English unit
* History of measurement

References

External links

* [http://www.opsi.gov.uk/si/si1995/Uksi_19951804_en_2.htm UK: The Units of Measurement Regulations 1995]