Pounds to Kilograms Calculator
Convert pounds to kilograms quickly and accurately.
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Enter your values and click Calculate
How It Works
The exact conversion factor defined by international agreement is 1 pound = 0.45359237 kilograms. Equivalently, 1 kilogram = 2.20462262 pounds. The calculator multiplies your pound value by 0.45359237 (or divides by 2.20462) to produce the kilogram result. Both operations are mathematically identical — the choice of which factor to use is a matter of convention. The conversion factor originates from the International Yard and Pound Agreement of 1959, which standardized the pound relative to the kilogram. The result is rounded to four decimal places for everyday use, though the underlying factor has more digits for scientific precision.
Examples
Body Weight
A person weighing 150 lbs converted to kilograms.
Result: 150 lbs is approximately 68.0389 kg.
Weight Limit
A 100 lb weight limit expressed in kilograms.
Result: 100 lbs equals 45.3592 kg.
Heavy Parcel
A 50 lb package being shipped internationally.
Result: 50 lbs equals approximately 22.6796 kg.
Frequently Asked Questions
How many kilograms are in a pound?
One pound equals exactly 0.45359237 kilograms by international definition. For most everyday purposes, 0.4536 kg per pound is sufficiently accurate. The reverse — kilograms to pounds — uses the factor 2.20462.
Why divide by 2.20462?
Because there are 2.20462 pounds per kilogram, dividing by that number reverses the conversion and gives kilograms. Multiplying by 0.4536 achieves the same result and is slightly easier to calculate mentally for quick estimates.
Is this accurate for medical use?
This uses the standard internationally agreed conversion factor, which is used in clinical settings worldwide. For prescribing medications by body weight, always verify the patient's weight with a calibrated clinical scale rather than relying on self-reported figures.