Convert Stone to Kilogram (st → kg)

Converting stones to kilograms is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in stones

   Start with the number of stones (st) you want to convert.
2. 2
   Multiply by 6.350293

   The conversion factor from st to kg is 6.350293. Multiply your value by this number.
3. 3
   Read the result in kilograms

   The result is your value in kilograms (kg).

Multiply the value in stones by 6.350293. For the reverse direction, multiply by 0.157473.

• ✓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.

What is the 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.

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

What is the Kilogram?

The kilogram is the base SI unit of mass. Since May 2019, it has been defined by fixing the numerical value of Planck's constant to exactly 6.62607015 × 10⁻³⁴ joule-seconds — a major shift from the previous definition based on a physical platinum-iridium artifact (the International Prototype Kilogram or 'Le Grand K') stored at the BIPM near Paris since 1889. This redefinition links the kilogram to a fundamental constant of nature, making it reproducible by any sufficiently equipped laboratory. The kilogram is the global standard for body weight (most countries quote weight in kilograms), grocery sales, scientific measurements, and engineering. One liter of pure water at 4°C has a mass of almost exactly 1 kg — a coincidence designed into the original 1795 definition. The kilogram relates to the gram (1,000 g = 1 kg), the metric ton (1,000 kg = 1 t), and the pound (1 kg ≈ 2.205 lb).

• Human body weight in most of the world
• Grocery and retail food quantities in Europe
• Scientific and engineering mass measurements