How Many Kilograms in a Stone?

Multiply the stones by 6.35 to get kilograms (kilos). For a figure that must be exact, use the full factor, 6.35029318. 9 stone, for example, is 57.15 kg, and 15 stone is 95.25 kg.

Round the final answer, not the factor. A factor cut short to one decimal place drifts further off with every stone, while rounding once at the end keeps the error tiny.

To go the other way, divide kilograms by the same factor or use kilograms to stones.

A weight such as 10 st 6 lb has two parts, and both need converting. The simplest route is to turn the whole thing into pounds first: 10 st 6 lb is 146 lb, which is 66.22 kg.

You can also convert the parts separately and add them. 10 st is 63.5 kg and 6 lb is 2.722 kg, which gives the same total.

Do not treat the pounds as a decimal. 10.6 stone is 67.31 kg, noticeably heavier than 10 st 6 lb.

Multiply the stones by six, then add a third of the stones. For 18 stone, that is 108 plus 6, which lands close to the exact 114.3 kg.

The shortcut runs slightly low, by well under one percent, so it suits a quick check rather than a form. For anything you write down, use the full factor or the converter above.