Pounds to Kilograms Converter (lb to kg)

Pounds are what a US bathroom scale, a gym plate or an airline check-in desk shows, while doctors, sports federations and almost every country outside the US record mass in kilograms. The two units are tied together by the 1959 international yard and pound agreement, which fixed the pound at exactly 0.45359237 kg, so a pound-to-kilogram answer never depends on whose table you use.

Enter a weight in pounds and the kilogram figure appears at once; the second chart runs the other way for readings met abroad, such as a 23 kg baggage rule or a clinic scale. The US and the UK use the same avoirdupois pound, so one factor serves both.

How to use this tool

1. Type a value in the Pound box to see it in kilograms, or type in the Kilogram box to convert the other way.
2. Press ⇄ to swap the two units, or Load example for a typical value.
3. Check the charts below for common values; for other units, open the Weight & Mass converter.

Formula

kg = lb × 0.45359237

lb = kg ÷ 0.45359237 (≈ 2.20462)

Both factors come from exact definitions: 1 kilogram = 2.20462262185 pounds and 1 pound = 0.45359237 kilograms (shown to 12 significant digits).

Example

Two conversions worked with the same factors the converter uses:

180 lb × 0.45359237 ≈ 81.6466 kg

82 kg × 2.20462262185 ≈ 180.779 lb

Pound to Kilogram chart

Common values from pounds to kilograms, rounded to four decimal places.

Kilogram to Pound chart

The reverse direction for values people often look up.

Everyday weights in pounds

Quick mental estimate

Halve the pounds, then take away a tenth of that half: 180 lb → 90 − 9 = 81 kg. The shortcut multiplies by 0.45, about 0.8% under the exact factor.

Use the converter or the charts when the exact figure matters.

The two units

Pound (lb): The avoirdupois pound has been defined since 1959 as exactly 0.45359237 kilograms and is divided into 16 ounces. It is the everyday unit of weight in the US.

Kilogram (kg): The kilogram is the SI base unit of mass. Since 2019 it has been defined by fixing the value of the Planck constant, replacing the platinum-iridium prototype kept near Paris.