The gram (originally gramme; SI unit symbol g) is a unit of mass in the

International System of Units The International System of Units, known by the international abbreviation SI in all languages and sometimes pleonastically as the SI system, is the modern form of the metric system and the world's most widely used system of measurement. E ...

(SI) equal to one one thousandth of a

kilogram The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially ...

. Originally defined as of 1795 as "the absolute weight of a volume of pure water equal to

the cube ''The'' () is a grammatical article in English, denoting persons or things that are already or about to be mentioned, under discussion, implied or otherwise presumed familiar to listeners, readers, or speakers. It is the definite article in En ...

of the hundredth part of a metre cm³], and at the temperature of Melting point">melting ice">Melting_point_of_w.html" ;"title="Cubic centimetre">cm³], and at Melting point of water">the temperature of Melting point">melting ice", 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

and the gram a derived unit. In 1960, the new

defined a ''gram'' as one one-thousandth of a kilogram (i.e., one gram is 1×10⁻³ kg). The kilogram, 2019 redefinition of the SI base units">as of 2019, is defined by the International Bureau of Weights and Measures from the fixed numerical value of the Planck constant (), which is kg⋅m²⋅s⁻¹.

Official SI symbol

The only unit symbol for gram that is recognised by the

(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 permit the use of abbreviations such as "gr" (which is the symbol for grains),National Institute of Standards and Technology (October 2011). Butcher, Tina; Cook, Steve; Crown, Linda et al. eds
"Appendix C – General Tables of Units of Measurement"
(PDF)
''Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices''
. NIST Handbook. 44 (2012 ed.). Washington, D.C.: U.S. Department of Commerce, Technology Administration, National Institute of Standards and Technology. ISSNbr>0271-4027

OCLC OCLC, Inc., doing business as OCLC, See also: is an American nonprofit cooperative organization "that provides shared technology services, original research, and community programs for its membership and the library community at large". It was ...

. Retrieved 30 June 2012. "gm" ("g⋅m" is the SI symbol for gram- metre) or "Gm" (the SI symbol for gigametre).

History

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. French ''gramme'' was taken from the Late Latin term '. This word—ultimately from Greek (''grámma''), "letter"—had adopted a specialised meaning in Late Antiquity of "one twenty-fourth part of an ounce" (two oboli), corresponding to about 1.14 modern grams. This use of the term is found in the ''carmen de ponderibus et mensuris'' ("poem about weights and measures") composed around 400 AD. There is also evidence that the Greek was used in the same sense at around the same time, in the 4th century, and survived in this sense into Medieval Greek, while the Latin term did not remain current in Medieval Latin and was recovered in Renaissance scholarship. The gram was the base unit of mass in the 19th-century centimetre–gram–second system of units (CGS). The CGS system co-existed with the

metre–kilogram–second system of units The MKS system of units is a physical system of measurement that uses the metre, kilogram, and second (MKS) as base units. It forms the base of the International System of Units (SI), though SI has since been redefined by different fundamental ...

(MKS), first proposed in 1901, during much of the 20th century, but the gram was displaced by the

as the base unit for mass when the MKS system was chosen for the SI base units in 1960.

Uses

The gram is today the most widely used unit of measurement for non-liquid ingredients in cooking and grocery shopping worldwide. 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.

Conversion factors

* 1 gram (g) = 15.4323583529 grains (gr) * 1 grain (gr) = 0.06479891 grams * 1 avoirdupois ounce (oz) = 28.349523125 grams * 1 troy ounce (ozt) = 31.1034768 grams * 100 grams (g) = 3.527396195 ounces (oz) * 1 carat (ct) = 0.2 grams * 1 gamma (γ) = 10⁻⁶ grams * 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) * 500 grams (g) = 1 jin in the Chinese units of measurement.

Comparisons

*1 gram is roughly equal to the mass of 1 small paper clip or pen cap. *The Japanese

1 yen coin The is the smallest denomination of the Japanese yen currency. Historically they were initially made of both silver and gold in the early 1870s. Issues facing the Japanese government at the time included wanting to adopt the gold standard, and c ...

has a mass of 1 gram, lighter than the British penny (3.56 g), the

United States penny The cent, the United States one-cent coin (symbol: ¢), often called the "penny", is a unit of currency equaling one one-hundredth of a United States dollar. It has been the lowest face-value physical unit of U.S. currency since the abolition o ...

(2.5 g), the Euro cent (2.30 g), and the

Australian 5 cent coin The Australian five-cent coin (Nickel) (originally called a "zac") is the lowest-denomination circulating coin of the decimal Australian dollar introduced in 14 February 1966, replacing the pre-decimal sixpence. It has been the lowest-denomina ...

(2.80 g).

Notes

References

{{Authority control Units of mass Centimetre–gram–second system of units