How to convert lb to kg
kg = lb × 0.45359237. The scale factor is the source-unit factor divided by the destination-unit factor.
Worked example
A parcel labeled 10 lb converts to 4.5359237 kg.
- Start with 10 lb.
- Multiply 10 by 0.45359237.
- Report 4.5359237 kg, rounded to the precision of your original measurement.
Use the full pound-to-kilogram factor for shipping calculations and round only the final result. Packaging mass is additional if your original reading excluded it.
Check the reverse conversion
1 kg = 2.204622622 lb. Use the kilogram to pound converter to calculate in the opposite direction. This has its own formula and reference table.
Definitions that matter
Pounds and ounces here are avoirdupois units, not troy units for precious metals. A tonne is 1,000 kg; it is not a US short ton or imperial long ton. Mass is not gravitational force.
The base unit for this category is kg. One lb corresponds to 0.45359237 kg; one kg corresponds to 1 kg. These definitions explain the relationship rather than relying on a rounded display value.
Sources and precision
Definitions: NIST Guide to the SI. Calculations use double precision; the tool defaults to a readable rounded result, while tables show up to ten significant digits. Displaying more digits does not increase the accuracy of the original measurement.
Read our calculation methodology and content standards, or continue with kilograms, pounds and exact conversion factors.