Quick answer: There are exactly 14 pounds in a stone. So 10 stone is 140 lb, 12 stone is 168 lb and half a stone is 7 lb. In metric terms one stone is 6.35 kg, because each pound is 0.45359237 kg. To turn stones into pounds, multiply by 14; to go back, divide by 14.
It is one of the first imperial facts British children pick up from bathroom scales, and one of the easiest to forget when a weight is given in pounds alone. Below is a picture of what 14 pounds looks like, a stones-to-pounds table and a short history of why the number is 14. For kilograms and other units, start at our weight conversions hub.
How many pounds are in a stone?
A stone contains exactly 14 pounds, with no rounding. To convert, multiply the stones by 14 and add any extra pounds. Someone who weighs 11 st 6 lb therefore weighs 11 × 14 + 6 = 160 lb.
Because each pound is 16 ounces, a stone is also 224 ounces. In grams it is 6,350.29 g, which is why the usual shortcut is “a stone is about six and a third kilos”.
How do you convert pounds to stones?
Divide the pounds by 14: the whole number is the stones and the remainder is the pounds left over. For 180 lb, 14 goes into 180 twelve times (168 lb), leaving 12 lb, so the answer is 12 st 12 lb.
Be careful with calculator answers. 180 ÷ 14 = 12.86, but that does not mean 12 st 86 lb or 12 st 8 lb; the .86 is a fraction of a stone. Our kg to stone and pounds guide explains this trap in more detail.
| Stones | Pounds | Stones | Pounds |
|---|---|---|---|
| 1 st | 14 lb | 11 st | 154 lb |
| 2 st | 28 lb | 12 st | 168 lb |
| 3 st | 42 lb | 13 st | 182 lb |
| 4 st | 56 lb | 14 st | 196 lb |
| 5 st | 70 lb | 15 st | 210 lb |
| 6 st | 84 lb | 16 st | 224 lb |
| 7 st | 98 lb | 17 st | 238 lb |
| 8 st | 112 lb | 18 st | 252 lb |
| 9 st | 126 lb | 19 st | 266 lb |
| 10 st | 140 lb | 20 st | 280 lb |
For the same weights in kilograms, see the stone to kg chart.
Why is a stone 14 pounds?
Because the wool trade fixed it there in the Middle Ages. Encyclopaedia Britannica records that a royal statute of 1389 set the stone of wool at 14 pounds and the sack of wool at 26 stones, as England needed consistent measures for its wool exports.
Before and for a long time after that, “stone” meant different things for different goods and places. Britannica notes a glass stone of just 5 pounds and stones ranging from 4 to 32 pounds over time. The 14 lb version is the one that survived, and it is the only stone in use today.
How does the stone fit with other imperial weights?
| Unit | In pounds | In stones | Metric |
|---|---|---|---|
| Ounce (oz) | 1/16 lb | 1/224 st | 28.35 g |
| Pound (lb) | 1 lb | 1/14 st | 453.59 g |
| Stone (st) | 14 lb | 1 st | 6.35 kg |
| Hundredweight (UK cwt) | 112 lb | 8 st | 50.80 kg |
| Ton (UK long ton) | 2,240 lb | 160 st | 1,016.05 kg |
The United States does not use the stone at all, and its hundredweight is 100 lb rather than 112 lb. American sources will therefore give body weight in pounds only; the pounds to kg converter handles those figures directly.
Frequently asked questions
How many pounds is half a stone?
Half a stone is 7 pounds, or about 3.18 kg.
How many pounds are in 10 stone?
10 stone is 140 pounds, because 10 × 14 = 140.
How many ounces are in a stone?
A stone is 224 ounces: 14 pounds × 16 ounces per pound.
Do Americans use stones?
No. In the United States body weight is given in pounds only. The stone is used mainly in the UK and Ireland.
Sources
- Encyclopaedia Britannica: stone (unit of weight).
- Weights and Measures Act 1985, section 1: definition of the pound.