Skip to content
Pounds and kilograms are two of the many units used for the measurement of mass. Physical quantities need units for their measurement. We need standard well-defined units for measurement of physical quantities.
Although both pound and kilogram are units of mass but there are some profound differences between these two units of mass. A pound is a unit of measuring mass that belongs to the imperial system of units. A kilogram on the other hand is a SI unit of mass.
Before looking at the difference between pound and kilogram let us first get an idea about kilogram and pound mass.
Kilogram Definition
One kilogram is equal to the mass (a platinum-iridium alloy cylinder) kept at International Bureau of Weights and Measures, at Sevres, near Pairs, France.
Originally 1 Kg was defined as the mass of 1 liter of water at $4^0C$ because at $4^0C$ water has maximum density and maximum volume.
Pound Definition
Pound or pound-mass (written as lb) like Kilogram is also a unit of measurement of mass used in imperial (FPS system of unit ), United States customary.
The Avoirdupois system is used to define the mass of 1lb of weight. The avoirdupois system (abbreviated avdp) is a measurement system of weights that uses pounds and ounces as units.
The United States and countries of the Commonwealth of Nations agreed upon common definitions for the pound and the yard. Since 1 July 1959, the international avoirdupois pound has been defined as exactly 0.45359237 kg. For most calculations purpose we consider
1 pound mass = 0.45 Kg
kg vs lbs in tabular form
| Kilogram | Pound |
| Kg is SI unit of mass | Pound is imperial unit of mass |
| Short form or abbreviation for Kilogram is $Kg$ | The short-form or abbreviation for Pound is $lb$ or $lbm$ This is because the unit is descended from the Roman *libra* (hence the abbreviation “lb”). |
| Kilogram is widely used unit of mass. | The pound is used mostly in UK and USA. |
| 1Kg=2.204 pounds | 1 Pound = 0.453Kg |
| Kilogram is the unit that is only used for measurement of mass | The pound is used for both mass and force. Also, note that Pound-mass is not the same as pound-force. |
Frequently Asked Questions
1 pound mass = 0.45 Kg
No, pound and Kg are different units for mass. A kilogram is the SI unit of mass and a pound is an imperial unit of mass. To convert from kg to pound, multiply the kg unit by 2.20462
1 kg = 2.2 lb
and to convert from pound to kg, multiply the pound unit by 0.453592
1 lb = 0.45 kg
References and further reading
- Difference Between Mass and Weight
- International System of units
- Imperial System of units