= 2.20462442018 pounds

In physics, mass is a property of a physical body. It is the measure of an object's resistance to acceleration (a change in its state of motion) when a force is applied. It also determines the strength of its mutual gravitational attraction to other bodies. In the theory of relativity a related concept is the mass–energy content of a system. The SI unit of mass is the kilogram (kg).

Mass is not the same as weight, even though we often calculate an object's mass by measuring its weight with a spring scale, rather than comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity, but it would still have the same mass. This is because weight is a force, while mass is the property that (along with gravity) determines the strength of this force.

The standard International System of Units (SI) unit of mass is the kilogram (kg). The kilogram is 1000 grams (g), first defined in 1795 as one cubic decimeter of water at the melting point of ice. Then in 1889, the kilogram was redefined as the mass of the international prototype kilogram, and as such is independent of the meter, or the properties of water. As of January 2013, there are several proposals for redefining the kilogram yet again, including a proposal for defining it in terms of the Planck constant.

Mass units | Symbol | Definition | Relation to SI units |
---|---|---|---|

atomic mass unit, unified | u; AMU | ≈ 1.660538921(73)×10−27 kg | |

atomic unit of mass, electron rest mass | me | ≈ 9.10938291(40)×10−31 kg | |

bag (coffee) | ≡ 60 kg | = 60 kg | |

bag (Portland cement) | ≡ 94 lb av | = 42.63768278 kg | |

barge | ≡ 22 1⁄2 short ton | = 20411.65665 kg | |

carat | kt | ≡ 3 1⁄6 gr | = 205.1965483 mg |

carat (metric) | ct | ≡ 200 mg | = 200 mg |

clove | ≡ 8 lb av | = 3.62873896 kg | |

crith | ≈ 89.9349 mg | ||

dalton | Da | ≈ 1.660538921(73)×10−27 kg | |

dram (apothecary; troy) | dr t | ≡ 60 gr | = 3.8879346 g |

dram (avoirdupois) | dr av | ≡ 27 11⁄32 gr | = 1.7718451953125 g |

electronvolt | eV | ≡ 1 eV (energy unit) / c2 | = 1.78266184(45)×10−36 kg |

gamma | γ | ≡ 1 μg | = 1 μg |

grain | gr | ≡ 1⁄7000 lb av | ≡ 64.79891 mg |

grave | gv. | grave was the original name of the kilogram | ≡ 1 kg |

hundredweight (long) | long cwt or cwt | ≡ 112 lb av | = 50.80234544 kg |

hundredweight (short); cental | sh cwt | ≡ 100 lb av | = 45.359237 kg |

kilogram | kg | ≡ mass of the prototype near Paris (≈ mass of 1 L of water) | ≡ 1 kg (SI base unit) |

kip | kip | ≡ 1000 lb av | = 453.59237 kg |

mark | ≡ 8 oz t | = 248.8278144 g | |

mite | ≡ 1⁄20 gr | = 3.2399455 mg | |

mite (metric) | ≡ 1⁄20 g | = 50 mg | |

ounce (apothecary; troy) | oz t | ≡ 1⁄12 lb t | = 31.1034768 g |

ounce (avoirdupois) | oz av | ≡ 1⁄16 lb | = 28.349523125 g |

ounce (US food nutrition labelling) | oz | ≡ 28 g | = 28 g |

pennyweight | dwt; pwt | ≡ 1⁄20 oz t | = 1.55517384 g |

point | ≡ 1⁄100 ct | = 2 mg | |

pound (avoirdupois) | lb av | ≡ 0.45359237 kg = 7000 grains | ≡ 0.45359237 kg |

pound (metric) | ≡ 500 g | = 500 g | |

pound (troy) | lb t | ≡ 5760 grains | = 0.3732417216 kg |

quarter (imperial) | ≡ 1⁄4 long cwt = 2 st = 28 lb av | = 12.70058636 kg | |

quarter (informal) | ≡ 1⁄4 short ton | = 226.796185 kg | |

quarter, long (informal) | ≡ 1⁄4 long ton | = 254.0117272 kg | |

quintal (metric) | q | ≡ 100 kg | = 100 kg |

scruple (apothecary) | s ap | ≡ 20 gr | = 1.2959782 g |

sheet | ≡ 1⁄700 lb av | = 647.9891 mg | |

slug; geepound; hyl | slug | ≡ 1 ɡ0 × 1 lb av × 1 s2/ft | ≈ 14.593903 kg |

stone | st | ≡ 14 lb av | = 6.35029318 kg |

ton, assay (long) | AT | ≡ 1 mg × 1 long ton ÷ 1 oz t | = 32.6 g |

ton, assay (short) | AT | ≡ 1 mg × 1 short ton ÷ 1 oz t | = 29.16 g |

ton, long | long tn or ton | ≡ 2240 lb | = 1016.0469088 kg |

ton, short | sh tn | ≡ 2000 lb | = 907.18474 kg |

tonne (mts unit) | t | ≡ 1000 kg | = 1000 kg |

wey | ≡ 252 lb = 18 st | = 114.30527724 kg | |

Zentner | Ztr. | Definitions vary. |