Formula
1 lb = 0.45359237 kg
kilograms = pounds × 0.45359237
How to convert
- Start with the weight in pounds.
- Multiply it by 0.45359237, the exact number of kilograms in one international avoirdupois pound.
- Round only the final result to the precision your task needs.
The pound used here is the international avoirdupois pound, the everyday unit used for body weight, packages, gym equipment, and groceries in the US and commonly in the UK. Since 1959, it has been defined as exactly 0.45359237 kilograms.
For everyday reading, two or three decimal places are usually enough. Shipping documents, laboratory work, or repeated calculations may justify retaining more digits.
Practical examples
10 lb × 0.45359237 = 4.5359237 kg50 lb × 0.45359237 = 22.6796185 kg150 lb × 0.45359237 = 68.0388555 kg
Conversion table
| Pounds (lb) | Kilograms (kg) |
|---|---|
| 1 | 0.453592 |
| 5 | 2.267962 |
| 10 | 4.535924 |
| 25 | 11.339809 |
| 50 | 22.679619 |
| 100 | 45.359237 |
| 150 | 68.038856 |
| 200 | 90.718474 |
Reference standard
The calculations follow the exact international avoirdupois pound relationship published in NIST Handbook 44, Appendix B. The BIPM kilogram reference describes the SI mass unit used on the metric side.
See how PoundsCalculator handles constants, validation, and rounding.
For more whole-number values, use the 1–300 lb to kg chart.
Questions people ask
How many kilograms are in one pound?
One international avoirdupois pound is exactly 0.45359237 kilograms.
What is 150 lb in kg?
150 pounds is 68.0388555 kilograms, usually rounded to 68.04 kg.
Should I divide or multiply to convert lb to kg?
Multiply pounds by 0.45359237. Dividing by about 2.20462 gives the same direction but is less direct.
Does this work for body weight and luggage?
Yes. The unit conversion is the same. For baggage, also check the airline’s current policy because limits and rounding practices vary.