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For the Chinese unit of mass, see Stone (Chinese mass).

The stone is a unit of weight and mass. 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 14 pounds and to 6.35029318 kilograms.

Eight stone make a hundredweight in the Imperial system.

The plural form of stone is correctly stone, though stones is sometimes used, not usually by natives of the British Isles. The abbreviation is st.

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.

lier definitions of both sack and stone as units of measure, and set a standard for each.

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^[1] including:

Although no longer an official unit of measure, 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 (road distances and speed enforcement area are still expressed officially in miles and miles per hour respectively) by metric units in official use (a similar usage persists in Canada, decal) and other contexts is the kilogram. In official use, provision is usually made for the public to express body weight in either stone or kilograms (similar allowance is made for measuring height in feet and inches). For example, on a National Health Service website both Imperial and metric units are used ^[2].

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

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

• UK: The Units of Measurement Regulations 1995

Notes: