Stone (st)
Definition
The stone (symbol st) is a British imperial unit of mass equal to exactly 14 avoirdupois pounds, or 6.35029318 kilograms. It is still used in the United Kingdom and Ireland to express human body weight.
History
Stones for weighing goods were used across Europe from antiquity, with values varying by region and commodity. England standardized several mercantile stones; the wool stone of 14 pounds proved most enduring.
The Weights and Measures Act of 1835 abolished most regional stones but retained the 14-pound stone for general use. Although the United Kingdom adopted the metric system for most legal trade in 1985, the stone remains a customary unit for personal body weight on home scales, in newspapers, and in everyday conversation.
Standard reference
Defined as 14 international avoirdupois pounds: exactly 6.35029318 kg. The Weights and Measures Act 1985 (UK) permits its continued informal use.
Common conversions
| 1 st | = 6.35029318 kg |
|---|---|
| = 14 lb | |
| = 224 oz | |
| = 6,350.29 g |