The short answer: 1 stone = 6.35029 kg
A stone is an imperial unit of weight equal to 14 pounds. Since one pound is defined as exactly 0.45359237 kg, one stone is 14 × 0.45359237 = 6.35029 kg. That figure is exact, not an approximation — so every conversion in this guide is precise to the gram.
Stone to kg table
| Stones | Kilograms | Pounds |
|---|---|---|
| 5 st | 31.7515 kg | 70 lb |
| 6 st | 38.1018 kg | 84 lb |
| 7 st | 44.4521 kg | 98 lb |
| 8 st | 50.8023 kg | 112 lb |
| 9 st | 57.1526 kg | 126 lb |
| 10 st | 63.5029 kg | 140 lb |
| 11 st | 69.8532 kg | 154 lb |
| 12 st | 76.2035 kg | 168 lb |
| 13 st | 82.5538 kg | 182 lb |
| 14 st | 88.9041 kg | 196 lb |
| 15 st | 95.2544 kg | 210 lb |
| 16 st | 101.6047 kg | 224 lb |
| 18 st | 114.3053 kg | 252 lb |
| 20 st | 127.0059 kg | 280 lb |
Stones and pounds to kg
Body weight is usually given as stones and pounds — 12 st 6 lb, for instance. Convert it in two steps: stones × 6.35029, plus pounds × 0.45359237. So 12 st 6 lb is 12 × 6.35029 + 6 × 0.45359237 = 78.9249 kg. For any value, the stone to kg converter does the arithmetic, including the pounds remainder.
Why the UK still talks in stones
The UK metricated trade and industry decades ago, but body weight is the holdout: people say "I'm 11 stone", not "I'm 70 kilograms". GP records, gym scales and clothing brands all still quote stones alongside kilograms, which is why the conversion stays one of the most searched weight questions in Britain.
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