## Definitions

### Pound of mass

The pound is a unit of mass according to the Imperial and US customary systems of units. Many definitions of the pound can be found throughout history, but today the international (avoirdupois) pound is standardized as exactly 0.45359237 kilograms. The symbol used for pound is 'lb' (from the Roman libra that is the equivalent to pound mass unit). Sometimes the lbm or lb-m abbreviation is used to distinguish it from the lbf or lb-f pound, which is a unit of force.

The relationships of pound to other mass units are shown in the following table:

Unit | Symbol | [lb] |
---|---|---|

Grain | gr | |

Dram | dr | |

Ounce | oz | |

Ton (short) | cwt | |

Kilogram | kg | |

Metric tonne | tn |

### Kilogram

Kilogram [kg] is a unit of mass according to the SI system of units. It was originally conceived as the mass of pure water included in a volume equal to 1 litre (10cm x 10cm x 10cm cube), at a temperature of 4°C (triple point of water). Today, it is defined as the mass that is equal to the mass of a particular prototype specimen, preserved by the International Bureau of Weights and Measures. Although kilogram is the base SI unit of mass, the SI multiple and fraction mass units are defined relative to the gram [g], because the word kilogram already contains the prefix 'kilo-' (for 1000). One kilogram is equal to 1000 grams.

The relationship of kilogram [kg] with other mass units are shown in the following table:

Unit | Symbol | [kg] |
---|---|---|

Nanogram | ng | |

Microgram | μg | |

Milligram | mg | |

Gram | g | |

Megagram (tonne) | Mg (t) | |

Pound | lb | |

Ounce | oz |

### How to convert pounds to kilograms (lb to kg)

- Multiply mass in lb with 0.45359237
- The result is the mass in kilograms

For example 400lb is 400x0.45359237 = 181.436948 kg

### How to convert kilograms to pounds (kg to lb)

- Divide mass in kg by 0.45359237
- The result is the mass in lb

For example 100 kg is 100/0.45359237 ≈ 220.4623 lb

### Conversion table from lb to kg

In the following table some typical masses in pounds are converted to kilograms:

[lb] | [kg] |
---|---|

0.25 | |

0.5 | |

0.75 | |

1 | |

2 | |

3 | |

4 | |

5 | |

6 | |

7 | |

8 | |

9 | |

10 | |

12 | |

15 | |

20 | |

25 | |

30 | |

35 | |

40 | |

45 | |

50 | |

60 | |

70 | |

80 | |

90 | |

100 | |

150 | |

200 |

### Conversion table from [kg] to [lb]

In the following table some typical masses in kilograms are converted to pounds:

[kg] | [lb] |
---|---|

0.25 | |

0.5 | |

0.75 | |

1 | |

2 | |

3 | |

4 | |

5 | |

6 | |

7 | |

8 | |

9 | |

10 | |

12 | |

15 | |

20 | |

25 | |

30 | |

35 | |

40 | |

45 | |

50 | |

60 | |

70 | |

80 | |

90 | |

100 | |

150 | |

200 |