Unit converter
Pounds to Kilograms Converter
Convert pounds into kilograms with one calculation. A pound is defined as exactly 0.45359237 kilograms, fixed by the 1959 international agreement, so the conversion is precise rather than rounded. Enter a mass in pounds and the tool shows kilograms, plus a table of the figures people look up most. The pound-to-kilogram swap is needed for body weight when a US scale reads in pounds but a doctor wants kilos, for converting American recipe weights, sizing dumbbells marked in pounds for a metric gym log, and reading shipping or produce weights across the two systems.
1 pound = 0.453592 kilograms
Common pounds to kilograms values
| Pounds | Kilograms |
|---|---|
| 1 lb | 0.453592 kg |
| 2 lb | 0.907185 kg |
| 5 lb | 2.268 kg |
| 10 lb | 4.5359 kg |
| 20 lb | 9.0718 kg |
| 50 lb | 22.6796 kg |
| 100 lb | 45.3592 kg |
How to convert
- Start with the mass written in pounds.
- Multiply by 0.45359237, since one pound is exactly 0.45359237 kilograms.
- The result is that mass in kilograms.
- Go the other way by dividing kilograms by 0.45359237, or multiplying by about 2.2046226.
- For a mental shortcut, halve the pounds and shave a little off: 100 lb is near 45 kg, since half of 100 is 50 minus about 5.
kilograms = pounds × 0.45359237
A pound is defined as exactly 0.45359237 kilograms, so multiplying a pound figure by that constant gives kilograms. Dividing kilograms by 0.45359237 returns pounds. Because the constant is the legal definition, the conversion is exact.
- lb
- the mass in pounds you begin with
- 0.45359237
- kilograms in one pound, by definition
Worked example
A 150 lb gym member logging their weight is 150 multiplied by 0.45359237, which is about 68.04 kilograms. A 45 lb weight plate, the common US size, equals 45 times 0.45359237, roughly 20.41 kg, close to the 20 kg metric plate but not identical.
Key facts
- One pound is exactly 0.45359237 kg; one kilogram is about 2.2046226 lb.
- A 45 lb US barbell plate is about 20.41 kg, slightly heavier than a 20 kg plate.
- A 50 lb airline bag limit equals roughly 22.68 kg.
- A newborn weighed at 8 lb is about 3.63 kg.
Tips
- For body weight, halve the pounds and trim about a tenth to picture the kilo figure.
- When matching US plates to a metric log, note 45 lb is just over 20 kg, not exactly equal.
- Keep full decimals through the sum and round the kilogram answer only at the end.
Frequently asked questions
How many kilograms are in 1 pound?+
Exactly 0.45359237 kilograms. This precise value was set by the 1959 yard and pound agreement.
How do I turn pounds into stone first?+
Divide pounds by 14 for stone, or skip straight to kilos by multiplying the pounds by 0.45359237.
What is 200 lb in kg?+
200 pounds is about 90.72 kilograms, a touch over fourteen stone.
Is the pound-to-kilogram figure exact?+
Yes. The pound is defined as exactly 0.45359237 kg, so no rounding enters beyond the decimals you display.
Things to watch
- Avoid the rough 1 lb = 0.5 kg shortcut for anything precise, as it overstates the mass by about 10 percent.
Sources
Last updated: 2026-01-01
Conversions use internationally defined factors. Provided for general use; verify critical measurements independently.