If you've ever looked at a British health report, watched a UK boxing match, or tried to understand your weight on a European scale, you've likely encountered the stone unit. Stone is a traditional British unit of weight that remains in everyday use across the UK and Ireland for measuring body weight. Converting between kilograms and stone is essential for anyone navigating between metric and imperial measurement systems.
One stone equals exactly 6.35029318 kilograms or 14 pounds. The stone unit has been used in Great Britain for centuries and was standardized in 1985 by the Weights and Measures Act. While the UK officially uses the metric system for trade, stone persists in casual body-weight discussions, medical settings, and sports like boxing and horse racing.
| Kilograms (kg) | Stone (st) | Stone + Pounds |
|---|---|---|
| 40 kg | 6.30 st | 6 st 4.2 lbs |
| 50 kg | 7.87 st | 7 st 12.2 lbs |
| 55 kg | 8.66 st | 8 st 9.3 lbs |
| 60 kg | 9.45 st | 9 st 6.3 lbs |
| 65 kg | 10.24 st | 10 st 3.3 lbs |
| 70 kg | 11.02 st | 11 st 0.3 lbs |
| 75 kg | 11.81 st | 11 st 11.3 lbs |
| 80 kg | 12.60 st | 12 st 8.4 lbs |
| 85 kg | 13.39 st | 13 st 5.4 lbs |
| 90 kg | 14.17 st | 14 st 2.4 lbs |
| 100 kg | 15.75 st | 15 st 10.5 lbs |
| 120 kg | 18.90 st | 18 st 12.6 lbs |
If you weigh 75 kg and someone from the UK asks your weight in stone, you'd say "about 11 stone 11." UK doctors typically record weight in kilograms but discuss it with patients in stone. Gym equipment in the UK often displays both units, but many locals still think in stone.
When calculating BMI using the imperial formula, you need weight in stone and height in feet/inches: BMI = (Stone × 14 + Pounds) × 703 ÷ (Height in inches)². For metric calculations, simply use kg and meters: BMI = kg ÷ m².
Boxing weight classes in the UK are often discussed in stone. For example, the heavyweight division starts at 14 stone (about 89 kg), while middleweight is around 11 st 6 lbs (approximately 72.5 kg). Understanding these conversions helps international fans follow UK sports coverage.
For rough estimates: divide kg by 6.35 to get stone. A simpler approximation is to divide by 6 and subtract about 5% of the result. For example, 72 kg ÷ 6 = 12, then subtract 0.6 ≈ 11.4 stone (actual: 11.34 stone — close enough for everyday use).
Stone is deeply embedded in British culture for body weight. Despite metrication efforts since the 1960s, public preference kept stone alive for personal weight measurements. The UK government permits its use alongside metric units for body weight in medical and retail contexts.
Our converter uses the exact factor of 6.35029318, which is the internationally agreed standard. The results are precise to multiple decimal places, suitable for any practical purpose.
Stone is primarily used in the United Kingdom and Ireland. It is not used in the United States, Canada, Australia, or New Zealand, where pounds or kilograms are the standard body weight units.
First multiply the stone value by 14, add the pounds, then multiply the total by 0.453592. For example, 11 stone 4 lbs = (11 × 14 + 4) × 0.453592 = 158 × 0.453592 = 71.67 kg.
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