gram | |
---|---|

General information | |

Unit system | SI |

Unit of | Mass |

Symbol | g |

Conversions | |

1 g in ... | ... is equal to ... |

SI base units | 10^{−3} kilograms |

CGS units | 1 gram |

Imperial units U.S. customary | 0.0352740 ounces |

Atomic mass units | 6.02214076×10^{23} Da |

The **gram** (originally **gramme**;^{[1]} SI unit symbol **g**) is a unit of mass in the International System of Units (SI) equal to one thousandth of a kilogram.

Originally defined as of 1795 as "the absolute weight of a volume of pure water equal to the cube of the hundredth part of a metre [1 cm^{3}], and at the temperature of melting ice",^{[2]} the defining temperature (≈0 °C) was later changed to 4 °C, the temperature of maximum density of water.

By the late 19th century, there was an effort to make the base unit the kilogram and the gram a derived unit. In 1960, the new International System of Units defined a *gram* as one one-thousandth of a kilogram (i.e., one gram is 1×10^{−3} kg). The kilogram, as of 2019, is defined by the International Bureau of Weights and Measures from the fixed numerical value of the Planck constant (h).^{[3]}^{[4]}

The only unit symbol for gram that is recognised by the International System of Units (SI) is "g" following the numeric value with a space, as in "640 g" to stand for "640 grams" in the English language. The SI disallows use of abbreviations such as "gr" (which is the symbol for grains),^{[5]}^{: C-19 } "gm" ("g⋅m" is the SI symbol for gram-metre) or "Gm" (the SI symbol for gigametre).

The word *gramme* was adopted by the French National Convention in its 1795 decree revising the metric system as replacing the *gravet* (introduced in 1793 simultaneously with a base measure called *grave*, of which *gravet* was a subdivision). Its definition remained that of the weight of a cubic centimetre of water.^{[6]}^{[7]}

French *gramme* was taken from the Late Latin term * gramma*. This word—ultimately from Greek γράμμα (

The gram was the base unit of mass in the 19th-century centimetre–gram–second system of units (CGS). The CGS system coexisted with the metre–kilogram–second system of units (MKS), first proposed in 1901, during much of the 20th century, but the gram was displaced by the kilogram as the base unit for mass when the MKS system was chosen for the SI base units in 1960.

The gram is the most widely used unit of measurement for non-liquid ingredients in cooking and grocery shopping worldwide.^{[11]}^{[12]} Liquid ingredients are often measured by volume rather than mass.

Many standards and legal requirements for nutrition labels on food products require relative contents to be stated per 100 g of the product, such that the resulting figure can also be read as a percentage.

- 1 gram (g) ≈ 15.43236 grains (gr)
- 1 grain (gr) ≈ 0.0647989 grams
- 1 avoirdupois ounce (oz) ≈ 28.3495 grams
- 1 troy ounce (ozt) = 31.1034768 g (exact, by definition)
- 100 grams (g) ≈ 3.52740 ounces (oz)
- 1 carat (ct) = 0.2 grams
- 1 gamma (γ) = 10
^{−6}grams^{[13]}^{[14]} - 1 undecimogramme = 1 "eleventh-gram" = 10
^{−11}grams in the historical quadrant–eleventh-gram–second system (QES system) a.k.a. hebdometre–undecimogramme–second system (HUS system)^{[15]} - 500 grams (g) = 1 jin in the Chinese units of measurement.

- 1 gram is roughly equal to the mass of 1 small paper clip or pen cap.
- The Japanese 1 yen coin has a mass of 1 gram,
^{[16]}lighter than the British penny (3.56 g), the United States penny (2.5 g), the Euro cent (2.30 g), and the Australian 5 cent coin (2.80 g).