The gram (originally gramme; SI unit symbol g) is a

unit Unit may refer to: Arts and entertainment * UNIT, a fictional military organization in the science fiction television series ''Doctor Who'' * Unit of action, a discrete piece of action (or beat) in a theatrical presentation Music * ''Unit'' (alb ...

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementar ...

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 In science and engineering, the weight of an object is the force acting on the object due to gravity. Some standard textbooks define weight as a Euclidean vector, vector quantity, the gravitational force acting on the object. Others define weigh ...

of a

volume Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). The de ...

of pure

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

equal to the cube of the hundredth part of a

metre The metre (British spelling) or meter (American spelling; see spelling differences) (from the French unit , from the Greek noun , "measure"), symbol m, is the primary unit of length in the International System of Units (SI), though its pref ...

cm³],_and_at_

cm³],_and_at_Melting_point_of_water">the_temperature_of_Melting_point.html" "title="Melting_point_of_water.html" ;"title="Cubic_centimetre.html" ;"title=" Cubic centimetre">cm³], and at Melting point of water">the temperature of Melting point">melting Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which inc ...

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 (measurement), 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 Scientific notation, 1×10⁻³ kg). The kilogram, as of 2019, is defined by the

International Bureau of Weights and Measures The International Bureau of Weights and Measures (french: Bureau international des poids et mesures, BIPM) is an intergovernmental organisation, through which its 59 member-states act together on measurement standards in four areas: chemistry, ...

from the fixed numerical value of the

Planck constant The Planck constant, or Planck's constant, is a fundamental physical constant of foundational importance in quantum mechanics. The constant gives the relationship between the energy of a photon and its frequency, and by the mass-energy equivale ...

(), 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 A grain is a small, hard, dry fruit (caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legumes ...

),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.

ISSN An International Standard Serial Number (ISSN) is an eight-digit serial number used to uniquely identify a serial publication, such as a magazine. The ISSN is especially helpful in distinguishing between serials with the same title. ISSNs ...

br>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-

) or "Gm" (the SI symbol for

giga Giga ( or ) is a unit prefix in the metric system denoting a factor of a short-scale billion or long-scale milliard (109 or ). It has the symbol G. ''Giga'' is derived from the Greek word (''gígas''), meaning "giant". The ''Oxford English Dic ...

metre).

History

The word ''gramme'' was adopted by the French

National Convention The National Convention (french: link=no, Convention nationale) was the parliament of the Kingdom of France for one day and the French First Republic for the rest of its existence during the French Revolution, following the two-year National ...

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 Late Latin ( la, Latinitas serior) is the scholarly name for the form of Literary Latin of late antiquity.Roberts (1996), p. 537. English dictionary definitions of Late Latin date this period from the , and continuing into the 7th century in t ...

term '. This word—ultimately from Greek (''grámma''), "letter"—had adopted a specialised meaning in

Late Antiquity Late antiquity is the time of transition from classical antiquity to the Middle Ages, generally spanning the 3rd–7th century in Europe and adjacent areas bordering the Mediterranean Basin. The popularization of this periodization in English ha ...

of "one twenty-fourth part of an ounce" (two

oboli The obol ( grc-gre, , ''obolos'', also ὀβελός (''obelós''), ὀβελλός (''obellós''), ὀδελός (''odelós''). "nail, metal spit"; la, obolus) was a form of ancient Greek currency and weight. Currency Obols were u ...

), 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 Medieval Greek (also known as Middle Greek, Byzantine Greek, or Romaic) is the stage of the Greek language between the end of classical antiquity in the 5th–6th centuries and the end of the Middle Ages, conventionally dated to the Ottoman co ...

, while the Latin term did not remain current in

Medieval Latin Medieval Latin was the form of Literary Latin used in Roman Catholic Western Europe during the Middle Ages. In this region it served as the primary written language, though local languages were also written to varying degrees. Latin functioned ...

and was recovered in

Renaissance The Renaissance ( , ) , from , with the same meanings. is a period in European history marking the transition from the Middle Ages to modernity and covering the 15th and 16th centuries, characterized by an effort to revive and surpass ideas ...

scholarship. The gram was the base unit of mass in the 19th-century

centimetre–gram–second system of units The centimetre–gram–second system of units (abbreviated CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time. All CGS mechanical units a ...

(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 The SI base units are the standard units of measurement defined by the International System of Units (SI) for the seven base quantities of what is now known as the International System of Quantities: they are notably a basic set from which all o ...

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

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

(gr) * 1 grain (gr) = 0.06479891 grams * 1

avoirdupois ounce The ounce () is any of several different units of mass, weight or volume and is derived almost unchanged from the , an Ancient Roman unit of measurement. The avoirdupois ounce (exactly ) is avoirdupois pound; this is the United States custom ...

(oz) = 28.349523125 grams * 1

troy ounce Troy weight is a system of units of mass that originated in 15th-century England, and is primarily used in the precious metals industry. The troy weight units are the grain, the pennyweight (24 grains), the troy ounce (20 pennyweights), and the ...

(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 The history of the metric system began during the Age of Enlightenment with measures of length and weight derived from nature, along with their decimal multiples and fractions. The system became the standard of France and Europe within half a ...

system) a.k.a. hebdometre–undecimogramme–second system (HUS system) * 500 grams (g) = 1 jin in the

Chinese units of measurement Chinese units of measurement, known in Chinese as the ''shìzhì'' ("market system"), are the traditional units of measurement of the Han Chinese. Although Chinese numerals have been decimal (base-10) since the Shang dynasty, Shang, several Chine ...

Comparisons

*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, lighter than the British penny (3.56 g), the United States penny (2.5 g), the

Euro cent There are eight euro coin denominations, ranging from one cent to two euros (the euro is divided into a hundred cents). The coins first came into use in 2002. They have a common Obverse and reverse, reverse, portraying a map of Europe, but each cou ...

(2.30 g), and the Australian 5 cent coin (2.80 g).

Notes

References

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