Convert pounds to kilograms. Multiply by 0.45359237 for an exact result, with reference tables for body weight, baggage and gym plates.

The formula

kilograms = pounds × 0.45359237

This factor is exact, not approximate. Since the international yard and pound agreement of 1959, one pound has been defined as exactly 0.45359237 kilograms, so this direction of the conversion loses no precision at all.

To go the other way, divide by 0.45359237. See kg to lbs.

Quick reference

Pounds	Kilograms
1 lb	0.4536 kg
2.205 lb	1 kg
5 lb	2.268 kg
10 lb	4.536 kg
25 lb	11.34 kg
50 lb	22.68 kg
100 lb	45.36 kg

Body weight

Pounds	Kilograms
100 lb	45.4 kg
120 lb	54.4 kg
140 lb	63.5 kg
150 lb	68.0 kg
160 lb	72.6 kg
180 lb	81.6 kg
200 lb	90.7 kg
220 lb	99.8 kg

Gym plates

Weight plates are manufactured to whichever system the gym was equipped in, and the two sets are close enough to be mistaken for each other but not close enough to match:

Imperial plate	Metric equivalent	Nearest metric plate
45 lb	20.41 kg	20 kg
35 lb	15.88 kg	15 kg
25 lb	11.34 kg	10 kg
10 lb	4.54 kg	5 kg

An Olympic barbell is 20 kg, which is 44.1 lb, but is almost always labelled 45 lb in the United States. A “225 lb” bench — bar plus two 45 lb plates a side — is 102.1 kg, not the 100 kg it is often assumed to equal.

Cooking

Pounds	Grams
1/4 lb	113 g
1/2 lb	227 g
1 lb	454 g
2 lb	907 g

A pound of butter is 454 g, which is why American recipes scaled into metric so often land on numbers like 113 g rather than a round 100 g.

Estimating in your head

Halve it, then take off 10%. 150 lb halves to 75, minus 7.5 is 67.5 kg — the true answer is 68.0 kg. That is within 0.8%, close enough for a suitcase and not close enough for a prescription.

Pounds to kilograms