How to convert pounds to kilograms
To convert a measurement in pounds to kilograms, multiply the value by 0.45359237. The conversion factor comes from the relationship between both units and the kilogram.
For example, to convert 5 lb to kilograms: 5 × 0.45359237 = 2.267962 kg.
What is a pound?
A pound is an imperial and US customary unit of mass equal to 16 ounces or exactly 0.45359237 kilograms. The pound derives from the Roman 'libra' (hence the symbol 'lb'). The international avoirdupois pound was fixed at exactly 0.45359237 kg by the 1959 international yard and pound agreement between English-speaking nations.
Common uses of pounds include: Body weight in the US and UK; Grocery and produce pricing in the US; Bodybuilding and weightlifting loads; Shipping weights for parcels in the US.
What is a kilogram?
A kilogram is the SI base unit of mass, equal to 1,000 grams or approximately 2.205 pounds. Originally defined in 1795 as the mass of one liter of water, the kilogram was fixed by a platinum-iridium cylinder from 1889 until 2019, when it was redefined in terms of the Planck constant. It is the only SI base unit whose name carries a prefix.
Common uses of kilograms include: Body weight in most countries; Grocery and produce pricing (price per kg); Shipping and freight weight; Scientific and laboratory mass measurements.
When you need to convert pounds to kilograms
People in the US and UK who track body weight, lift weights, or ship parcels often need to express pounds in kilograms for medical forms, international shipping, or fitness apps that default to metric. A 150 lb person weighs about 68 kg.
Pounds to kilograms worked examples
Here are some common values converted:
1 lb = 0.45359237 kg 5 lb = 2.267962 kg 10 lb = 4.535924 kg 50 lb = 22.679619 kg 100 lb = 45.359237 kg
Frequently asked questions
How many kilograms are in one pound?
One pound (lb) equals 0.45359237 kilograms (kg). Multiply any value in pounds by 0.45359237 to convert to kilograms.
How do I convert pounds to kilograms?
Multiply the value in pounds by 0.45359237. For example, 5 lb × 0.45359237 = 2.267962 kg.
How do I convert kilograms to pounds?
Multiply the value in kilograms by 2.204623, or divide by 0.45359237. Use the swap button on the converter above to reverse the direction.
Is the pound to kilogram conversion exact?
Yes. Since 1959 the international pound is defined as exactly 0.45359237 kg, so all weight conversions between metric and avoirdupois units use exact factors.
What is the formula for pounds to kilograms?
The formula is: kg = lb × 0.45359237. This comes from the definition of both units relative to the kilogram.