Quick answer: One stone equals 6.35029318 kilograms, so to convert stone to kg you multiply by 6.35. For example, 10 stone is 63.50 kg, 12 stone is 76.20 kg and 15 stone is 95.25 kg. The chart below lists every whole stone from 1 to 30, with pounds and kilograms side by side.
Bathroom scales, gym apps and NHS forms do not always agree on units, and the stone is the one most British people still think in. Use the converter for an exact figure, or print the chart and stick it inside a cupboard door. For pounds, grams and the rest, our weight conversions hub collects every guide in one place.
Stone to kg converter
stone= kg ( lb)Decimal stones work too: type 11.5 for eleven and a half stone. If your weight is written as stones and pounds, such as 11 st 5 lb, use the odd-pounds table further down or our dedicated stones-and-pounds converter.
How do you convert stone to kg?
Multiply the number of stones by 6.35029318 to get kilograms. For everyday use, 6.35 is accurate to within a few grams per stone. The formula is: kg = stone × 6.35029318.
- Write the weight in stones. For 13½ stone, use 13.5.
- Multiply by 6.35. 13.5 × 6.35029318 = 85.73 kg.
- Round sensibly. Most scales show one decimal place, so 85.7 kg is the figure you would expect to see.
A quick mental shortcut is to multiply by 6, then add a third of the original number. For 12 stone: 12 × 6 = 72, plus 4 = 76 kg, against an exact answer of 76.20 kg. It slightly underestimates, but it is close enough for a rough check.
Stone to kg chart: 1 to 30 stone
Kilograms are rounded to two decimal places. Pounds are exact, because a stone is exactly 14 pounds.
| Stone | Pounds | Kilograms | Stone | Pounds | Kilograms |
|---|---|---|---|---|---|
| 1 st | 14 lb | 6.35 kg | 16 st | 224 lb | 101.60 kg |
| 2 st | 28 lb | 12.70 kg | 17 st | 238 lb | 107.95 kg |
| 3 st | 42 lb | 19.05 kg | 18 st | 252 lb | 114.31 kg |
| 4 st | 56 lb | 25.40 kg | 19 st | 266 lb | 120.66 kg |
| 5 st | 70 lb | 31.75 kg | 20 st | 280 lb | 127.01 kg |
| 6 st | 84 lb | 38.10 kg | 21 st | 294 lb | 133.36 kg |
| 7 st | 98 lb | 44.45 kg | 22 st | 308 lb | 139.71 kg |
| 8 st | 112 lb | 50.80 kg | 23 st | 322 lb | 146.06 kg |
| 9 st | 126 lb | 57.15 kg | 24 st | 336 lb | 152.41 kg |
| 10 st | 140 lb | 63.50 kg | 25 st | 350 lb | 158.76 kg |
| 11 st | 154 lb | 69.85 kg | 26 st | 364 lb | 165.11 kg |
| 12 st | 168 lb | 76.20 kg | 27 st | 378 lb | 171.46 kg |
| 13 st | 182 lb | 82.55 kg | 28 st | 392 lb | 177.81 kg |
| 14 st | 196 lb | 88.90 kg | 29 st | 406 lb | 184.16 kg |
| 15 st | 210 lb | 95.25 kg | 30 st | 420 lb | 190.51 kg |
What if your weight includes odd pounds?
Look up the whole stones in the chart above, then add the kilograms for the extra pounds from this table. For 11 st 5 lb, that is 69.85 kg + 2.27 kg = 72.12 kg.
| Extra pounds | Add (kg) | Extra pounds | Add (kg) |
|---|---|---|---|
| 1 lb | 0.45 | 8 lb | 3.63 |
| 2 lb | 0.91 | 9 lb | 4.08 |
| 3 lb | 1.36 | 10 lb | 4.54 |
| 4 lb | 1.81 | 11 lb | 4.99 |
| 5 lb | 2.27 | 12 lb | 5.44 |
| 6 lb | 2.72 | 13 lb | 5.90 |
| 7 lb (half a stone) | 3.18 |
For pound-only weights, the pounds to kilograms converter skips the stone step entirely.
Why is one stone exactly 6.35029318 kg?
Because the pound is defined in UK law as exactly 0.45359237 kg, and a stone is 14 of those pounds. Section 1 of the Weights and Measures Act 1985 fixes the pound against the kilogram, and 14 × 0.45359237 = 6.35029318 with no rounding. The kilogram itself is defined internationally through the Planck constant, so the stone ultimately traces back to the SI.
Where is the stone still used in the UK?
The stone survives mainly for body weight. Ask someone in Britain or Ireland what they weigh and the answer is often given in stones and pounds, even by people who buy everything else in kilograms. Typical places you will still meet it:
- Bathroom scales sold in the UK, many of which switch between st, lb and kg.
- The NHS BMI calculator, which accepts weight in stones and pounds as well as kilograms.
- Horse racing, where the weight a horse carries is given in stones and pounds on British racecards.
- Conversation, slimming clubs and older medical notes.
Shops, food labels and medicine doses use kilograms and grams, so converting is worth doing whenever accuracy matters. The weight converter covers every other combination, from ounces to tonnes.
Frequently asked questions
How many kg is 1 stone?
One stone is 6.35029318 kg, usually rounded to 6.35 kg.
What is 10 stone in kg?
10 stone is 63.50 kg, which is also 140 lb.
What is 15 stone in kg?
15 stone is 95.25 kg, or 210 lb.
How do I convert half a stone to kg?
Half a stone is 7 lb, which is 3.18 kg. So 12½ stone is 76.20 kg + 3.18 kg = 79.38 kg.
Is there a quick way to convert stone to kg in my head?
Multiply the stones by 6 and add a third of the original number. For 9 stone, 54 + 3 = 57 kg, close to the exact 57.15 kg.
Sources
- Weights and Measures Act 1985, section 1 (pound defined as 0.45359237 kg).
- BIPM: the International System of Units (definition of the kilogram).
- NHS: BMI calculator.