Convert Pounds to Kilograms
Convert pounds (lb) to kilograms (kg) instantly, with the formula, worked examples, and the mistakes to avoid.
- Milligram (mg)453,592.4
- Gram (g)453.5924
- Kilogram (kg)0.453592
- Tonne (t)0.000454
- Ounce (oz)16
- Pound (lb)1
- Don (돈)120.958
- Geun (근, 600g)0.755987
- Nyang (냥)12.0958
- Gwan (관)0.120958
🔒 Unit conversions are computed in your browser.
The pound-to-kilogram formula
The math is a single multiplication: take the weight in pounds (lb) and multiply by 0.4536 to get kilograms (kg). So kg = lb × 0.4536. A 150 lb body weight becomes 150 × 0.4536 = 68.04 kg, and a 50 lb airline baggage limit works out to 50 × 0.4536 = 22.68 kg. To go the other way, multiply kilograms by 2.2046 (the same as dividing by 0.4536). The exact factor is 0.45359237, but 0.4536 stays accurate to two decimal places for any everyday weight.
Where you'll actually use it
You mostly need lb → kg when reading US figures. International shipping is often priced by weight in pounds, so a 5 lb parcel is 5 × 0.4536 = 2.27 kg. Gym plates sold in the US are labeled 45 lb, which comes to 45 × 0.4536 = 20.41 kg, and a newborn weighing 8 lb is about 3.63 kg. Handy anchor points worth memorizing: 10 lb ≈ 4.54 kg, 100 lb ≈ 45.36 kg, and 220 lb ≈ 100 kg.
Easy things to get wrong
A few traps. First, this is the standard avoirdupois pound; the troy pound used for gold and silver is different, at 1 lb = 0.3732 kg. Second, don't confuse lb (mass) with lbf, or pound-force — they look alike but measure different things, so check the context. Third, mind the rounding: shipping and freight rates are usually rounded up, so a 22.68 kg parcel may be billed as 23 kg. For quick mental math, halve the pounds and trim about 10%.
Frequently asked questions
How many kilograms is one pound exactly?
One pound is defined as exactly 0.45359237 kg. For everyday use, 0.4536 is more than precise enough, and remembering that 1 lb is roughly 0.45 kg gets you close instantly.
How do I convert kilograms back to pounds?
Multiply the kilogram value by 2.2046. For example, 70 kg × 2.2046 = 154.3 lb. Dividing by 0.4536 gives you the exact same answer.
What's a fast way to estimate kg from a US body weight in pounds?
Halve the pound figure, then subtract about 10%. Half of 160 lb is 80, and minus 10% is roughly 72, close to the exact 72.58 kg. It's a good sanity check before trusting a full calculation.