How to convert pounds to kilograms
kg = x × 0.45359237
Use avoirdupois pounds, as used for body and package weights. Troy weights follow a different system.
Worked example
kg = 150 × 0.45359237
150 lb = 68.038855 kg.
Conversion table in both directions
Values are generated by the same engine as the interactive converter.
| Input | lb → kg | kg → lb |
|---|---|---|
| 1 | 0.453592 | 2.204623 |
| 5 | 2.267962 | 11.023113 |
| 10 | 4.535924 | 22.046226 |
| 25 | 11.339809 | 55.115566 |
| 50 | 22.679619 | 110.231131 |
| 100 | 45.359237 | 220.462262 |
Unit definitions and sources
These units measure mass, not force. Metric tonnes, US short tons, UK long tons and troy ounces have distinct definitions.
| Unit and system | Use | Definition | Relationship |
|---|---|---|---|
| Kilogram (kg); si | Common units | Kilogram measures mass. kg = (value in kg) × 1. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Pound (lb); us | Common units | Pound measures mass. kg = (value in lb) × 0.45359237. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
Sources: BIPM: International System of Units; NIST: SP 811 Appendix B.8: conversion factors; NIST: 2022 CODATA recommended constants; BIPM: SI prefixes
Precision of weight and mass conversions
These 2 weight and mass units convert through Kilogram (kg). 2 have an exact defined relationship to the base unit and 0 are conventional or measured values. Results and the tables on this page come from the same engine, so a table value can be checked against the converter directly.
Standard display shows up to six decimal places, switching to scientific notation for very large or small values. Calculation uses JavaScript binary floating point independently of display rounding, so extra digits are not a claim about measurement accuracy. Each unit lists its own source; a citation records where the definition comes from, not an independent review. See Conversion methodology for the review and correction process.