Pounds to Kilograms
Type a value in either box to convert between pounds and kilograms. The factor is 0.453592.
| Pounds | Kilograms |
|---|---|
| 1 lb | 0.453592 kg |
| 2 lb | 0.907185 kg |
| 3 lb | 1.360777 kg |
| 5 lb | 2.267962 kg |
| 10 lb | 4.535924 kg |
| 25 lb | 11.339809 kg |
| 50 lb | 22.679619 kg |
| 100 lb | 45.359237 kg |
How to use
- Enter a value in the Pounds field.
- The Kilograms figure appears immediately — no button to press.
- Typing in the Kilograms field converts back to Pounds the same way.
- Use the reference table for the values that come up most often.
Pounds to Kilograms formula
Converting pounds to kilograms is a single multiplication by 0.45359237.
kg = lb × 0.45359237
Why this factor: the pound and the kilogram are both defined against the kilogram, so dividing one definition by the other gives 0.45359237 directly. Both definitions are set out in full below.
To go the other way, divide by 0.45359237 — or use the Kilograms to Pounds converter, which is the same calculation reversed.
Worked example
Take 2 lb and multiply by the factor 0.45359237: the result is 0.907185 kg.
2 lb × 0.45359237 = 0.907185 kg
The converter above does this for any value you type, in either direction.
What is a pound?
The pound is the primary unit of weight in the United States.
Definition: Exactly 0.45359237 kilogram since the 1959 International Yard and Pound Agreement — an exact definition, not a rounded one.
Where it is used: Body weight, grocery and produce pricing, shipping rates, and gym weights in the US.
Worth knowing: This is the avoirdupois pound. The troy pound used for precious metals is different (about 373 g).
What is a kilogram?
The kilogram is the SI base unit of mass — the reference for every other mass unit.
Definition: Since 2019 the kilogram has been defined by fixing the Planck constant at exactly 6.62607015×10⁻³⁴ joule-seconds, retiring the physical platinum-iridium cylinder that defined it for 130 years.
Where it is used: Universal in science, trade and everyday weighing outside the United States.
Pounds vs Kilograms
The pound is an imperial unit while the kilogram is an SI unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many kilograms are in a pound?
One pound equals 0.45359237 kilograms.
What is the formula to convert pounds to kilograms?
Multiply the number of pounds by 0.45359237. To reverse it, divide by 0.45359237 instead.
How do I convert kilograms back to pounds?
Divide by 0.45359237, which is the same as multiplying by 2.20462262.
How many kilograms are in 10 pounds?
10 lb works out to 4.535924 kg.
Is there anything to watch out for with pounds?
This is the avoirdupois pound. The troy pound used for precious metals is different (about 373 g).
How is the pound defined?
Exactly 0.45359237 kilogram since the 1959 International Yard and Pound Agreement — an exact definition, not a rounded one.