Pounds to Stone
Convert pounds (lb) to stone (st). Both measure mass and weight, and the conversion comes up in cooking, shipping, fitness work.
The Formula
``
stone = pounds × 0.0714285714286
pounds = stone × 14
`
One pound is 0.071429 stone, and one stone is 14 pounds.
Conversion Table
| Pounds | Stone |
|---|---|
| 1 lb | 0.071429 st |
| 2 lb | 0.142857 st |
| 5 lb | 0.357143 st |
| 10 lb | 0.714286 st |
| 25 lb | 1.7857 st |
| 50 lb | 3.5714 st |
| 100 lb | 7.1429 st |
| 500 lb | 35.7143 st |
| 1,000 lb | 71.4286 st |
The Other Direction
| Stone | Pounds |
|---|---|
| 1 st | 14 lb |
| 2 st | 28 lb |
| 5 st | 70 lb |
| 10 st | 140 lb |
| 25 st | 350 lb |
| 50 st | 700 lb |
| 100 st | 1,400 lb |
| 500 st | 7,000 lb |
| 1,000 st | 14,000 lb |
What Each Unit Is
Pounds (lb) — exactly 0.45359237 kilograms, by the 1959 international agreement. The Roman libra — which is why its symbol is lb — refined through the English avoirdupois system.
Stone (st) — exactly 14 pounds, or 6.35029318 kilograms. A medieval trade weight that varied by commodity until standardised at 14 lb in 1835.
A Sense of Scale
A bag of sugar is 2 lb- A newborn is 6–9 lb
- US body weight is given in pounds
- British body weight is often given in stone and pounds
- An adult is typically 9–14 stone
Precision
The factor 0.0714285714286 is exact by international agreement, not a rounded approximation. Any imprecision in a result comes from your input, not the conversion.
Watch Out For
- Effectively British-only. US sources give body weight in pounds alone.
In Code
`javascript
const poundToStone = (value) => value * 0.0714285714286;
``
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 lb with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 lb becomes | Error |
|---|---|---|---|
| 0 | 0 | 0 | 100.0000% |
| 1 | 0.1 | 13.7 | 40.0000% |
| 2 | 0.07 | 9.59 | 2.0000% |
| 3 | 0.071 | 9.727 | 0.6000% |
| 4 | 0.0714 | 9.7818 | 0.0400% |
The right number of significant figures is set by your input, not by the converter. If you measured pounds to three significant figures, the answer in stone is only good to three — writing more digits claims precision the measurement never had.