Stone (unit)

This article is about the European unit of mass. For Asian uses of 'stone', see Picul.

For the material made of rock, see Rock (geology).

A 16th-century bronze 1 stone weight emblazoned with the English coat of arms.

The stone or stone weight (abbreviation: st.) is an English and imperial unit of weight now equal to 14 avoirdupois pounds (6.35029318 kg).

England and other Germanic-speaking countries of northern Europe formerly used various standardized "stones" for trade, with their values ranging from about 5 to 40 local pounds (roughly 3 to 15 kg) depending on the location and objects weighed. The United Kingdom's imperial system adopted the wool stone of 14 pounds in 1835. With the advent of metrication, Europe's various "stones" were superseded or adapted to the kilogram from the mid-19th century on. The stone continues in customary use in Britain and Ireland for measuring body weight, but was prohibited for commercial use in the UK by the Weights and Measures Act of 1985.

Antiquity

A 2nd-century stone weight of 40 Roman pounds (~13 kg), beside a credit card for scale.

The name "stone" derives from the use of stones for weights, a practice that dates back into antiquity. The Biblical law against the carrying of "diverse weights, a large and a small" is more literally translated as "you shall not carry a stone and a stone (אבן ואבן), a large and a small". There was no standardized "stone" in the ancient Jewish world, but in Roman times stone weights were crafted to multiples of the Roman pound (about 327.54 g). Such weights varied in quality: the Yale Medical Library holds 10 and 50-pound examples of polished blackstone, while a 40-pound example at the Eschborn Museum is made of sandstone.

British Isles

England

The English stone under law varied by commodity and in practice varied according to local standards. The Assize of Weights and Measures, a statute of uncertain date from c. 1300, describes stones of 5 merchants' pounds used for glass; stones of 8 lbs. used for beeswax, sugar, pepper, alum, cumin, almonds, cinnamon, and nutmegs; stones of 12 lbs. used for lead; and the London stone of ​12 ¹⁄₂ lbs. used for wool. In 1350, Edward III issued a new statute fixing the stone of wool at 14 pounds, reaffirmed by Henry VII in 1495.

A nineteenth-century slide rule for estimating cattle carcass weights, calibrated in stones of 20, ​17 ¹⁄₂, 8 and 14 pounds.

In England, merchants traditionally sold potatoes in half-stone increments of 7 pounds. Live animals were weighed in stones of 14 lb; but, once slaughtered, their carcases were weighed in stones of 8 lb. Thus, if the animal's carcase accounted for ​⁸⁄₁₄ of the animal's weight, the butcher could return the dressed carcases to the animal's owner stone for stone, keeping the offal, blood and hide as his due for slaughtering and dressing the animal. Smithfield market continued to use the 8 lb stone for meat until shortly before the Second World War. The Oxford English Dictionary also lists:

Commodity	Number of Pounds
Wool	14, 15, 24
Wax	12
Sugar and spice	8
Beef and mutton	8

Scotland

The Scottish stone was equal to 16 Scottish pounds (17 lb 8 oz avoirdupois or 7.936 kg). In 1661, the Royal Commission of Scotland recommended that the Troy stone be used as a standard of weight and that it be kept in the custody of the burgh of Lanark. The tron (or local) stone of Edinburgh, also standardised in 1661, was 16 tron pounds (24 lb 1 oz avoirdupois or 9.996 kg). In 1789, an encyclopedic enumeration of measurements was printed for the use of "his Majesty's Sheriffs and Stewards Depute, and Justices of Peace, ... and to the Magistrates of the Royal Boroughs of Scotland" and provided a county-by-county and commodity-by-commodity breakdown of values and conversions for the stone and other measures. The Scots stone ceased to be used for trade when the Act of 1824 established a uniform system of measure across the whole of the United Kingdom, which at that time included all of Ireland.

Ireland

Before the early nineteenth century, as in England, the stone varied both with locality and with commodity. For example, the Belfast stone for measuring flax equaled 16.75 avoirdupois pounds.) The most usual value was 14 pounds. Among the oddities related to the use of the stone was the practice in County Clare of a stone of potatoes being 16 lb in the summer and 18 lb in the winter.

United Kingdom and Ireland

The 1772 edition of the Encyclopædia Britannica defined the stone:

STONE also denotes a certain quantity or weight of some commodities. A stone of beef, in London, is the quantity of eight pounds; in Hertfordshire, twelve pounds; in Scotland sixteen pounds.

The Weights and Measures Act of 1824, which applied to all of the United Kingdom, consolidated the weights and measures legislation of several centuries into a single document. It revoked the provision that bales of wool should be made up of 20 stones, each of 14 pounds, but made no provision for the continued use of the stone. Ten years later, a stone still varied from 5 pounds (glass) to 8 pounds (meat and fish) to 14 pounds (wool and "horseman's weight"). However, the Act of 1835 permitted using a stone of 14 pounds for trade but other values remained in use. James Britten, in 1880 for example, catalogued a number of different values of the stone in various British towns and cities, ranging from 4 lb to 26 lb. The value of the stone and associated units of measure that were legalised for purposes of trade were clarified by the Weights and Measures Act 1835 as follows:

Pounds	Unit	Stone	kg
1	1 pound	​1⁄14	0.4536
14	1 stone	1	6.350
28	1 quarter	2	12.70
112	1 hundredweight	8	50.80
2240	1 (long) ton	160	1016

In 1965, the then Federation of British Industry informed the British Government that its members favoured adopting the metric system. The Board of Trade, on behalf of the Government, agreed to support a ten-year metrication programme. There would be minimal legislation, as the programme was to be voluntary and costs were to be borne where they fell. Under the guidance of the Metrication Board, the agricultural product markets achieved a voluntary switchover by 1976. The stone was not included in the Directive 80/181/EEC as a unit of measure that could be used within the EEC for "economic, public health, public safety or administrative purposes", though its use as a "supplementary unit" was permitted. The scope of the directive was extended to include all aspects of the EU internal market as from 1 January 2010.

With the adoption of metric units by the agricultural sector, the stone was, in practice, no longer used for trade; and, in the Weights and Measures Act 1985, passed in compliance with EU directive 80/181/EEC, the stone was removed from the list of units permitted for trade in the United Kingdom. In 1983, in response to the same directive, similar legislation was passed in Ireland. The Act repealed earlier acts that defined the stone as a unit of measure for trade. (British law had previously been silent regarding other uses of the stone.)

The stone remains widely used in the UK and Ireland for human body weight: in those countries people may commonly be said to weigh, e.g., "11 stone 4" (11 stones and 4 pounds), rather than "72 kilograms" as in many other countries, or "158 pounds" (the conventional way of expressing the same weight in the US). The correct plural form of stone in this context is stone (as in, "11 stone" or "12 stone 6 pounds"); in other contexts, the correct plural is stones (as in, "Please enter your weight in stones and pounds"). In Australia and New Zealand, metrication has almost entirely displaced stone and pounds since the 1970s.

In many sports in both Britain and Ireland, such as professional boxing, wrestling and horse racing, the stone is used to express body weights.

Elsewhere

The use of the stone in the British Empire was varied. In Canada for example, it never had a legal status. Shortly after the United States declared independence, Thomas Jefferson, then Secretary of State presented a report on weights and measures to the U.S. House of Representatives. Even though all the weights and measures in use in the United States at the time were derived from English weights and measures, his report made no mention of the stone being used. He did, however, propose a decimal system of weights in which his "[decimal] pound" would have been 9.375 ounces (265.8 g) and the "[decimal] stone" would have been 5.8595 pounds (2.6578 kg).

A depiction of a medieval German scale weighing bales of wool according to the local stone.

Before the advent of metrication, units called "stone" (German: Stein; Dutch: steen; Polish: kamień) were used in many North-Western European countries. Its value, usually between 3 and 10 kg, varied from city to city and sometimes from commodity to commodity. The number of local "pounds" in a stone also varied from city to city. During the early 19th century, states such as the Netherlands (including Belgium) and the South Western German states, which had redefined their system of measures using the kilogramme des Archives as a reference for weight (mass), also redefined their stone to align it with the kilogram.

This table shows a selection of stones from various North European Continental cities:

City	Modern country	Term used	Weight of stone in kilograms	Weight of stone in local pounds	Comments
Dresden	Germany	Stein	10.15	22	Before 1841
			10.0	20	From 1841 onwards
Mecklenburg-Strelitz Berlin	Germany	schwerer Stein	10.296	22	heavy stone
		leichter Stein	5.148	11	light stone
Danzig (Gdańsk) Königsberg (Kaliningrad)	Poland Russia	grosser Stein	15.444	33	large stone
		kleiner Stein	10.296	22	small stone
Bremen	Germany	Steinflachs	9.97	20	stone of flax
		Stein Wolle und Federn	4.985	10	stone of wool and feathers
Oldenburg	Germany	Stein Flachs	9.692	20	stone of flax
		Steinwolle und Federn	4.846	10	stone of wool and feathers
Kraków	Poland	Stein	10.137	25
Osnabrück	Germany	Stein	4.941	10
Amsterdam	Netherlands	Steen	3.953	8	Before 1817
			3	3	"Metric stone" (after 1817)
Karlsruhe	Germany	Stein	5.00	10
Leipzig, Weimar	Germany	Stein	10.287	22
Breslau (Wrocław)	Poland	Stein	9.732	24
Antwerpen	Belgium	Steen	3.761	8
Prague	Czech Republic	Stein	10.29	20
Solothurn	Switzerland	Stein	5.184	10
Stockholm	Sweden	Sten	13.60	32	(32 Skålpund)
Warsaw	Poland	Kamieni	10.14	25	25 Funtów
Vilnius	Lithuania	Kamieni	14.992	40	40 Funtów
Vienna	Austria	Stein	11.20	20

Metric stone

Although the advent of the metric system spelt the demise of the stone as a unit of measure, the stone was used in some early discussions and implementations of the metric system. In his Philosophical essay written in 1668, John Wilkins proposed a system of measure whose unit of length, the standard, was approximately one metre and whose unit of mass was the mass of a cubic standard of rainwater (which would have been approximately 1,000 kg). He proposed that one tenth of this mass (100 kg) should be called a stone. In 1791, a few years before the French Revolutionary Government agreed on the metre as the basis of the metric system, Thomas Jefferson, in a report to Congress proposed that the United States should adopt a decimal currency system (which was adopted) and a decimal-based system of measure (which was not adopted). Jefferson's proposal for units of measure included a "decimal" pound equal to 9.375 ounces (265.8 g) in the "customary" system and a "decimal" stone of 10 "decimal" pounds or 5.8595 pounds (2.6578 kg).

Neither Wilkins' nor Jefferson's proposals were adopted; but, in the Netherlands, where the metric system was adopted in 1817, the pond (pound) was set equal to a kilogram. and the steen (stone), which had previously been 8 Amsterdam pond (3.953 kg), was redefined as being 3 kg.

See also

• English, imperial, and German units of measurement
• Sack, a unit of wool equal to 28 stone

External links

• UK: The Units of Measurement Regulations 1995