Pounds to kilograms
v1libraskilogramosHow it is worked out
Convert a weight in pounds to kilograms with the exact factor, such as 150 pounds, which is 68.04 kilograms.
One pound is exactly 0.45359237 kilograms, by international agreement since 1959. To go from pounds to kilograms, multiply by that number: 150 pounds is 68.04 kilograms. For a quick estimate, dividing the pounds by 2.2 gives almost the same answer.
The expression that runs
libras * 0.45359237The fields arrive with an example filled in: put your own numbers in and run it again. You can also edit the formula to fit your case.
What if the formula were yours?
This calculator is not hand-written: it is an Axioma formula. Open it in the editor to see how it is built, adapt it to your case and create the ones you need.
Step by step, with 150 pounds
Multiply the weight in pounds by 0.45359237, which is what one pound weighs in kilograms. 150 times 0.45359237 is 68.0388555, or 68.04 kilograms once rounded. There are no other steps: the conversion is a single multiplication.
The factor is exact because the pound is defined in terms of the kilogram, not the other way round. Since the international agreement of 1959, a pound is 0.45359237 kilograms by definition, so the result is as precise as the number you start from.
The shortcut of dividing by 2.2
A kilogram is about 2.2046 pounds, so dividing pounds by 2.2 gives a quick estimate: 150 over 2.2 is 68.18 kilograms. It is off by about 140 grams, under 0.25 %, which does not matter when weighing a suitcase or a person.
For a recipe, a medicine dose or freight charged by weight, the full factor is worth it. The error in the shortcut grows with the amount: on 2,000 pounds of cargo it is already almost two kilograms.
Where pounds still show up
The United States uses pounds for body weight, packaged food and most goods sold online, and in the United Kingdom body weight is often given in stones and pounds. Gyms, luggage allowances and product labels in English all mix the two systems.
A stone is fourteen pounds, so a weight given as 11 stone 4 is 158 pounds, and from there the same multiplication gives 71.67 kilograms. Every imperial weight ends up going through the pound on its way to the metric system.
Frequently asked questions
- How do I convert kilograms to pounds?
- The other way round: divide by 0.45359237, or multiply by 2.20462. A weight of 70 kilograms is 154.32 pounds. You can open this formula in the editor and swap the multiplication for a division.
- How many kilograms is 100 pounds?
- It is 45.36 kilograms: 100 times 0.45359237. It is handy for mental arithmetic, since every hundred pounds is about 45.36 kilograms: 200 pounds is 90.72 and 50 pounds is 22.68.
- Why is the abbreviation for pounds lb?
- It comes from the Latin libra, the Roman unit of weight, which is also where the Spanish word for pound comes from. The same root gives the pound sign used for money, £, which is a stylised L.