What is a Stone?

The stone equals exactly 14 pounds or 6.35029318 kilograms and remains the traditional British unit for personal body weight. Originally based on a stone literally used as a counterweight on a balance scale, the unit was standardized at 14 pounds by an Act of Parliament in 1835. While metrication has reduced its role in commerce, the stone persists in British everyday life — a person is described as '11 stone 4' (158 lb) rather than 72 kg — and is widely used in British and Irish weight-loss programs, medical contexts, and gym equipment. The stone is virtually unknown in the United States and most of the world. It relates to the pound (14 lb = 1 stone), the kilogram (1 stone ≈ 6.35 kg), and the long ton (160 stone = 1 long ton). Stones-and-pounds notation (like '11 st 4 lb') is the British equivalent of decimal kilograms.

Visual reference for how the stone relates to other weight units. Each row links to the full converter for that pair.

• Human body weight in the UK and Ireland
• British medical charts and patient records
• British boxing and wrestling press reports

• ✓1 stone = 14 lb = 6.35 kg exactly.
• ✓British speakers often say "11 stone 4" meaning 11 stone and 4 pounds — not 11.4 stone.
• ✓Multiply stones by 6.35 for a precise kg conversion.

• ✗Reading "11 stone 4" as 11.4 stone — it is 11 × 14 + 4 = 158 lb.
• ✗Using stones outside UK/Ireland contexts — audiences elsewhere will not understand.
• ✗Multiplying by 6 instead of 6.35 for a quick kg estimate — 5% error.