1 pound = 0.45359237 kg
1 lb = 0.453592 kg · type math like (12*4)+6.5
Pounds to kilograms is the conversion Americans need for international travel, medical forms abroad and fitness apps set to metric. It also matters for shipping, because international couriers price parcels by the kilogram even when the scale at home reads pounds.
Medical dosing is one of the most important uses. Many drug doses are calculated per kilogram of body weight, so US patients who know their weight in pounds need it converted before a dose is worked out. A 154 lb patient weighs 69.85 kg, and a dose of 5 mg per kilogram becomes 349 mg.
Fitness and sport are another everyday use. American gyms label dumbbells in pounds, while international powerlifting uses kilograms. A 45 lb plate is 20.41 kg, and a 315 lb squat, three plates per side plus the bar, is 142.9 kg. Boxing weight classes are set in pounds but are also published in kilograms for international bouts: the 147 lb welterweight limit is 66.68 kg.
Pet food and veterinary doses also use body weight. A 66 lb dog weighs 29.94 kg, and vets outside the US calculate medication on that figure.
Bowling balls range from 6 to 16 lb, which is 2.72 to 7.26 kg.
A quick check is that the kilogram number is always a bit less than half the pound number. 220 lb should land just under 100 kg (99.8 kg exactly). If your answer is more than the pound figure, you multiplied by 2.2 instead of dividing. For medical forms, record kilograms to one decimal place, which is the precision most clinics and hospital systems expect when calculating drug doses or body mass index.
kg = lb × 0.45359237
Reverse: 1 kg = 2.2046226 lb.
Convert a body weight of 180 lb to kilograms.
Answer: 180 lb = 81.6 kg.
| lb | kg |
|---|---|
| ¼ lb | 0.11339809 kg |
| ½ lb | 0.22679619 kg |
| ¾ lb | 0.34019428 kg |
| 1 lb | 0.45359237 kg |
| 2 lb | 0.90718474 kg |
| 3 lb | 1.3607771 kg |
| 4 lb | 1.8143695 kg |
| 5 lb | 2.2679619 kg |
| 6 lb | 2.7215542 kg |
| 7 lb | 3.1751466 kg |
| 8 lb | 3.628739 kg |
| 9 lb | 4.0823313 kg |
| 10 lb | 4.5359237 kg |
| 11 lb | 4.9895161 kg |
| 12 lb | 5.4431084 kg |
| 13 lb | 5.8967008 kg |
| lb | kg |
|---|---|
| 14 lb | 6.3502932 kg |
| 15 lb | 6.8038856 kg |
| 16 lb | 7.2574779 kg |
| 17 lb | 7.7110703 kg |
| 18 lb | 8.1646627 kg |
| 19 lb | 8.618255 kg |
| 20 lb | 9.0718474 kg |
| 25 lb | 11.339809 kg |
| 30 lb | 13.607771 kg |
| 40 lb | 18.143695 kg |
| 50 lb | 22.679619 kg |
| 75 lb | 34.019428 kg |
| 100 lb | 45.359237 kg |
| 250 lb | 113.39809 kg |
| 500 lb | 226.79619 kg |
| 1 000 lb | 453.59237 kg |
A 50 lb bag limit is 22.68 kg, just under the 23 kg limit used by most non-US airlines.
A 12 lb box is 5.44 kg, which may move it into a higher international price band than you expect.
180 lb is 81.6 kg.
Halving is close but overstates the kilograms by about 10%. 200 lb is 90.7 kg, not 100.
A troy pound is 12 troy ounces, or 0.373 kg. Gold and silver use troy units, not avoirdupois.
7 lb 8 oz is 7.5 lb, so it is 3.40 kg. Ignoring the 8 oz gives 3.18 kg, a 220 g error.
One avoirdupois pound is exactly 0.45359237 kg, or 16 ounces.
Origin. From the Roman libra, which is why the symbol is lb. Several English pounds existed (troy, tower, merchant) before avoirdupois became the standard trade pound.
Used today. US body weight, grocery labels, gym plates and shipping; in the UK people often give body weight in stone and pounds.
The kilogram is the SI base unit of mass, defined since 2019 through the Planck constant.
Origin. Originally the mass of a liter of water, then a metal cylinder from 1889 to 2019.
Used today. Used for nearly all mass measurements in commerce, medicine and science worldwide.
150 × 0.45359237 = 68.04 kg.
It comes from libra, the Roman unit of weight.
Halve the number and subtract 10% of the result: 160 lb → 80 − 8 = 72 kg. The exact answer is 72.57 kg.
No. The pound is defined as exactly 0.45359237 kg, and the redefinition did not change the size of the kilogram in practice.