The exact equivalent
A pound is exactly 0.45359237 kilograms. That is the legal definition, so this conversion is exact.
1 lb = 0.45359237 kg
1 kg = 2.20462262 lb
How to convert it by hand
Just multiply by the conversion factor. To go from pounds to kilograms, multiply by 0.453592; to come back, divide by that same number or multiply by 2.204623.
For example: 25 lb × 0.453592 = 11.3398 kg.
A tip that saves mistakes: check the result goes the way you expect. If kilograms are a smaller unit than pounds, the number has to come out bigger. If it comes out smaller, you divided when you should have multiplied.
Conversion table
| lb | kg |
|---|---|
| 1 | 0.4536 |
| 2 | 0.9072 |
| 5 | 2.268 |
| 10 | 4.5359 |
| 20 | 9.0718 |
| 50 | 22.6796 |
| 100 | 45.3592 |
Reference points to picture it
| Reference | Equals |
|---|---|
| 1 pound | 0.454 kg |
| A 45 lb barbell plate | 20.4 kg |
| A 150 lb person | 68 kg |
| A US short ton (2,000 lb) | 907.2 kg |
The trick for doing it in your head
Halve it and take off 10%. For 150 lb: 75 minus 7.5 gives 67.5 kg, against a true 68.04.
It is fine for getting by without a phone, but not for anything that depends on precision: in a recipe, on a building site or in a dose, use the exact conversion.