The exact conversion
Pounds to kilograms is the conversion you need when a US scale, a gym plate, or a recipe says lbs and the other side of the conversation uses kilograms. The pound on this page is the international avoirdupois pound, exactly 0.45359237 kilograms, the same pound used for body weight and groceries in the United States. It is not the troy pound used for precious metals, and it is not a casual “half kilo.” Half a kilogram is about 1.102 pounds, so treating a pound as 500 grams is off by about 10%.
The formula used above is kg = lb ÷ 2.204623. Both boxes stay in step, so you can start from either unit. Results are rounded for display; the factor itself is the legal definition, not a rounded shortcut.
Worked examples
Each line is the same formula with a new starting number. You can match it against the converter by typing the value on the left.
- 1 pound: 1 ÷ 2.204623 = 0.4536 kilograms.
- 150 pounds: 150 ÷ 2.204623 = 68.0389 kilograms.
- 200 pounds: 200 ÷ 2.204623 = 90.7185 kilograms.
Where the rounding matters
Divide by 2.2 for a quick estimate, then remember the exact factor is a little under that. One hundred fifty pounds is 150 × 0.45359237 = 68.039 kilograms, while 150 ÷ 2.2 is about 68.18. For a medical form or a shipping label, use the exact factor and round to a tenth of a kilogram, or to the hundredth if the form asks for it. Two hundred pounds is 90.719 kilograms, which most people would report as 90.7 kg.
The kilogram number is always smaller than the pound number, because a kilogram is heavier than a pound. If your result grew, the boxes were swapped. You can check any row by converting it back on the kg to lbs page: 68.039 kg returns to 150 lb, within ordinary rounding.
Conversion table: pounds to kg
| lb | kg |
|---|---|
| 1 lb | 0.454 kg |
| 5 lb | 2.268 kg |
| 10 lb | 4.536 kg |
| 20 lb | 9.072 kg |
| 50 lb | 22.68 kg |
| 100 lb | 45.359 kg |
| 120 lb | 54.431 kg |
| 150 lb | 68.039 kg |
| 180 lb | 81.647 kg |
| 200 lb | 90.718 kg |
| 250 lb | 113.398 kg |