National Physical Laboratory

How do I convert between kilograms and pounds? (FAQ - Mass & Density)

The relationship between the kilogram and the pound is defined exactly as:

1 lb = 0.453 592 37 kg

Note that the pound is defined as a proportion of the kilogram and not the other way around, so it is not strictly correct to say that 1 kg = 1/0.453 592 37 lb - even ignoring the fact that this reciprocal is not exact when expressed to eight significant figures as in the definition.

Last Updated: 25 Mar 2010
Created: 8 Oct 2007


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