Stone to Kilograms
Convert stone (st) to kilograms (kg). Both measure mass and weight, and the conversion comes up in cooking, shipping, fitness work.
The Formula
``
kilograms = stone × 6.35029318
stone = kilograms × 0.157473044418
`
One stone is 6.3503 kilograms, and one kilogram is 0.157473 stone.
Conversion Table
| Stone | Kilograms |
|---|---|
| 1 st | 6.3503 kg |
| 2 st | 12.7006 kg |
| 5 st | 31.7515 kg |
| 10 st | 63.5029 kg |
| 25 st | 158.7573 kg |
| 50 st | 317.5147 kg |
| 100 st | 635.0293 kg |
| 500 st | 3,175.15 kg |
| 1,000 st | 6,350.29 kg |
The Other Direction
| Kilograms | Stone |
|---|---|
| 1 kg | 0.157473 st |
| 2 kg | 0.314946 st |
| 5 kg | 0.787365 st |
| 10 kg | 1.5747 st |
| 25 kg | 3.9368 st |
| 50 kg | 7.8737 st |
| 100 kg | 15.7473 st |
| 500 kg | 78.7365 st |
| 1,000 kg | 157.473 st |
What Each Unit Is
Stone (st) — exactly 14 pounds, or 6.35029318 kilograms. A medieval trade weight that varied by commodity until standardised at 14 lb in 1835.
Kilograms (kg) — defined since 2019 by fixing the Planck constant — the SI base unit of mass. Originally the mass of a litre of water, then a platinum-iridium cylinder near Paris until 2019.
A Sense of Scale
British body weight is often given in stone and pounds- An adult is typically 9–14 stone
- A litre of water is 1 kg
- A laptop is 1.5–2 kg
- Checked baggage allowance is often 23 kg
Doing It in Your Head
Multiply by 19, then divide by 3. That is off by 0.27% — close enough to judge a
distance, a weight or a price, and not close enough to sign off on a drawing.
Exact Mental shortcut 63.5029 kg 63.3333 kg 635.0293 kg 633.3333 kg
Precision
The factor 6.35029318 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.
Watch Out For
- Effectively British-only. US sources give body weight in pounds alone.
In Code
`javascript
const stoneToKilogram = (value) => value * 6.35029318;
``
Where This Conversion Comes Up
- Cooking
- Shipping
- Fitness
- Medicine
- Manufacturing
How Many Decimals Do You Need?
Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 st with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 st becomes | Error |
|---|---|---|---|
| 0 | 6 | 822 | 5.5162% |
| 1 | 6.4 | 876.8 | 0.7827% |
| 2 | 6.35 | 869.95 | 0.0046% |
| 3 | 6.35 | 869.95 | 0.0046% |
| 4 | 6.3503 | 869.991 | 0.0001% |
The right number of significant figures is set by your input, not by the converter. If you measured stone to three significant figures, the answer in kilograms is only good to three — writing more digits claims precision the measurement never had.