Gram | |
---|---|

General information | |

Unit system | UCUM base unit and CGS unit |

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 | 0.0353 ounces |

The **gram** (originally **gramme**;^{[1]} SI unit symbol **g**) is a unit of mass in the metric system.

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.

However, 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 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), which is 6.62607015×10^{−34} kg⋅m^{2}⋅s^{−1}.^{[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 does not support the 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. Its definition remained that of the weight (*poids*) 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 fundamental unit of mass in the 19th-century centimetre–gram–second system of units (CGS). The CGS system co-existed with the meter-kilogramme-second system of units (MKS), first proposed in 1901, during much of the 20th century, but the gram has been displaced by the kilogram as the fundamental unit for mass when the MKS system was chosen for the SI base units in 1960.

The gram is today the most widely used unit of measurement for non-liquid ingredients in cooking and grocery shopping worldwide.^{[11]}^{[12]} Liquid ingredients may be 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) = 15.4323583529 grains (gr)
- 1 grain (gr) = 0.06479891 grams (g)
- 1 avoirdupois ounce (oz) = 28.349523125 grams (g)
- 1 troy ounce (ozt) = 31.1034768 grams (g)
- 100 grams (g) = 3.527396195 ounces
- 1 gram (g) = 5 carats (ct)
- 1 gram (g) = 8.98755179×10
^{13}joules (J) (by mass–energy equivalence) - 1 undecimogramme = 1 "eleventh-gram" = 10
^{−11}grams in the historic quadrant–eleventh-gram–second system (QES system) a.k.a. hebdometre–undecimogramme–second system (HUS system) (HUS system)^{[13]} - 500 grams (g) = 1 Jin in the Chinese units of measurement.

- 1 gram is roughly equal to 1 small paper clip or pen cap.
- The Japanese 1 yen coin has a mass of 1 gram,
^{[14]}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).