Weight Converter
Kilograms, pounds, and stone โ type in any box, read the others.
About this converter
Four boxes โ kilograms, pounds, stone and the pounds left over โ all live in every direction, with the full statement written out (70 kg = 154.3 lb = 11 st 0.3 lb) and a chart from 40 to 130 kg. Stone-and-pounds is included because it's still how body weight is spoken in the UK and Ireland, and most converters forget it.
The numbers behind it
The pound has been defined as exactly 0.45359237 kg since 1959, so โ like the inch โ this conversion is exact by definition. The working approximations: 1 kg โ 2.2 lb (memorise this one), a stone is exactly 14 lb โ 6.35 kg, and to go from pounds to kilograms roughly, halve and take off 10% (154 lb โ 77 โ ~70 kg โ). How the two systems came to coexist is a good story; ounces, grams and tonnes live in the full unit converter, and if the weight you're converting is your own, the BMI calculator takes either unit.
Frequently asked questions
How many pounds is 1 kg?
2.2046 lb โ the everyday '2.2' is accurate to a tenth of a percent. The exact definition runs the other way: 1 lb = 0.45359237 kg precisely.
How does the stone system work?
A stone is exactly 14 pounds, and UK body weight is spoken as stone plus leftover pounds: 11 st 4 lb is 158 lb or 71.7 kg. Nobody says '158 pounds' in Britain.
What is 70 kg in pounds?
154.3 lb โ or 11 stone 0.3 lb. The quick check: 70 ร 2.2 = 154.
How do I convert pounds to kg in my head?
Halve the pounds, then knock 10% off the result: 180 lb โ 90 โ 81 kg (true answer 81.6). Good to within a kilogram for body-weight ranges.