To convert pounds to kilograms, multiply by 0.45359237. 150 lb is 68.04 kg, 200 lb is 90.72 kg, and a 50 lb luggage limit is 22.68 kg.
Body weight, gym plates and baggage allowances in the US are given in pounds, while doctors, airlines and fitness apps elsewhere use kilograms. The chart covers typical adult weights.
How to use the lbs to kg converter
- Type the value in pounds into the box. Decimals are fine.
- The result in kilograms updates as you type, along with the working.
- Need the other way? Switch the direction menu, or open the kg to lbs converter.
Formula
The international avoirdupois pound is defined as exactly 0.45359237 kg (since 1959). The reverse factor, 2.20462262…, never ends, which is why kg → lb results are rounded.
Worked example
Convert a body weight of 150 lb to kg.
- 150 × 0.45359237 = 68.0389.
- Result: 68.04 kg.
Gym example: a standard 45 lb plate is 20.41 kg, close to but not the same as a 20 kg Olympic plate.
Pounds to kilograms chart
Common values, rounded to 2 decimal places.
| Pounds (lb) | Kilograms (kg) |
|---|---|
| 1 lb | 0.45 kg |
| 2 lb | 0.91 kg |
| 5 lb | 2.27 kg |
| 10 lb | 4.54 kg |
| 20 lb | 9.07 kg |
| 25 lb | 11.34 kg |
| 45 lb | 20.41 kg |
| 50 lb | 22.68 kg |
| 100 lb | 45.36 kg |
| 110 lb | 49.9 kg |
| 120 lb | 54.43 kg |
| 130 lb | 58.97 kg |
| 140 lb | 63.5 kg |
| 150 lb | 68.04 kg |
| 160 lb | 72.57 kg |
| 170 lb | 77.11 kg |
| 180 lb | 81.65 kg |
| 200 lb | 90.72 kg |
| 220 lb | 99.79 kg |
| 250 lb | 113.4 kg |
| 300 lb | 136.08 kg |
Where pounds are used
- Body weight: US scales, and the UK alongside stones (see stone to lbs converter).
- Air travel: US carriers cap checked bags at 50 lb (22.68 kg); many others use 23 kg (50.7 lb).
- Gyms: US plates come in 2.5, 5, 10, 25, 35 and 45 lb.
- Babies: US birth weights are given in pounds and ounces; 7 lb 8 oz is 3.40 kg.
Quick mental math
Halve it, then take off 10% of that. 180 lb: half is 90, minus 9 = 81 kg (exact: 81.65).
Related conversions
Going the other way: kg to lbs converter. Related pages: stone to lbs converter, lbs to stone converter, ounces to grams converter. For other units in the same family, use the full weight converter.
Caveats and assumptions
- Results show up to 10 significant digits; the chart is rounded for reading. Keep full precision for engineering, medical or legal work.
Frequently asked questions
How many kg is 1 lb?
Exactly 0.45359237 kg, a little under half a kilogram.
How many kg is 200 lbs?
90.72 kg.
Is 50 lb the same as 23 kg?
Not quite. 50 lb is 22.68 kg, and 23 kg is 50.71 lb. A bag that passes a 23 kg limit can fail a 50 lb limit.
Why is pound abbreviated lb?
From the Latin libra pondo, "a pound by weight."
Sources
- NIST — SI Units: Mass — kilogram and the exact avoirdupois pound
- NIST SP 811 Appendix B.9 — Conversion factors — pound (avoirdupois) to kilogram
This calculator gives estimates for planning and education. Check measurements, local codes, supplier specs and your school's official policy before relying on a result. See our disclaimer and how we build and check calculators.