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The gram (alternative spelling: gramme; unit symbol: g) is a
metric system The metric system is a that succeeded the decimalised system based on the introduced in France in the 1790s. The historical development of these systems culminated in the definition of the (SI), under the oversight of an international stan ...

unit Unit may refer to: Arts and entertainment * 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 ...
of
mass Mass is the quantity Quantity is a property that can exist as a multitude or magnitude, which illustrate discontinuity and continuity. Quantities can be compared in terms of "more", "less", or "equal", or by assigning a numerical value ...
. Originally defined as "the absolute weight of a volume of pure
water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for all known forms of , even though it provide ...

equal to the cube of the hundredth part of a
metre The metre ( Commonwealth spelling) or meter (American spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English o ...
cm3], and at the temperature of melting ice" (later at 4 °C, the temperature of maximum density of water). However, in a reversal of reference and defined units, a gram is now defined as one thousandth of the base unit, the
kilogram The kilogram (also kilogramme) is the base unit of mass Mass is the physical quantity, quantity of ''matter'' in a physical body. It is also a measure (mathematics), measure of the body's ''inertia'', the resistance to acceleration (change ...
, or Scientific notation, 1×10−3 kg, which itself is defined by the International Bureau of Weights and Measures, not in terms of grams, but by taking the fixed numerical value of the
Planck constant The Planck constant, or Planck's constant, is a fundamental physical constant A physical constant, sometimes fundamental physical constant or universal constant, is a physical quantity that is generally believed to be both universal in nature an ...
to be kg⋅m2⋅s−1.

# Official SI symbol

The only unit symbol for gram that is recognised by the
International System of Units The International System of Units, known by the international abbreviation SI in all languages and sometimes Pleonasm#Acronyms_and_initialisms, pleonastically as the SI system, is the modern form of the metric system and the world's most wi ...
(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 A grain is a small, hard, dry – with or without an attached or layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are s and . After being harvested, dry ...
),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 A serial number is a unique identifier A unique identifier (UID) is an identifier that is guaranteed to be unique among all identifiers used for those object ...
br>0271-4027
OCLC OCLC, Inc., doing business as A trade name, trading name, or business name is a pseudonym A pseudonym () or alias () (originally: ψευδώνυμος in Greek) is a fictitious name that a person or group assumes for a particular purpose, w ...
. 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 The National Convention (french: link=no, Convention nationale) was a parliament In modern politics and history, a parliament is a legislative body of government. Generally, a modern parliament has three functions: Representation (poli ...
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 written Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, kn ...
term '. This word—ultimately from Greek (''grámma''), "letter"—had adopted a specialised meaning in
Late Antiquity Late antiquity is a periodization Periodization is the process or study of categorizing the past into discrete, quantified named blocks of time.Adam Rabinowitz. It’s about time: historical periodization and Linked Ancient World Data'. Inst ...
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 use ...
), 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 or Byzantine Greek) 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 Fall of Constantino ...
, while the Latin term did not remain current in
Medieval Latin Medieval Latin was the form of Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share ...
and was recovered in
Renaissance The Renaissance ( , ) , from , with the same meanings. is a period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in ...

scholarship. 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
MKS system of units The MKS system of units is a physical system of measurement that uses the meter, kilogram, and second (MKS) as Base unit (measurement), base units. It forms the base of the International System of Units (SI), though SI has since been redefined by ...
, first proposed in 1901, during much of the 20th century, but the gram has been displaced by the
kilogram The kilogram (also kilogramme) is the base unit of mass Mass is the physical quantity, quantity of ''matter'' in a physical body. It is also a measure (mathematics), measure of the body's ''inertia'', the resistance to acceleration (change ...
as the fundamental unit for mass when the MKS system was chosen for the
SI base units The SI base units are the standard units of measurement A unit of measurement is a definite magnitude (mathematics), magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the ...

in 1960.

# Uses

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

# Conversion factors

* 1 gram (g) = 15.4323583529
grains A grain is a small, hard, dry – with or without an attached or layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are s and . After being harvested, dry ...
(gr) * 1 grain (gr) = 0.06479891 grams (g) * 1
avoirdupois ounce The ounce is the name of several different units of mass, weight In science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), organizes knowle ...
(oz) = 28.349523125 grams (g) * 1
troy ounce 1 troy ounce (1.097 avoirdupois ounces, 31.1 g) coin example ( Platinum Eagle) File:1000oz.silver.bullion.bar.underneath.jpg, A Good Delivery silver bar weighing Troy weight is a system of Physical unit, units of mass that originated in 15th-ce ...
(ozt) = 31.1034768 grams (g) * 100 grams (g) = 3.527396195 ounces * 1 gram (g) = 5 carats (ct) * 1 gram (g) = 8.98755179
joule The joule ( ; symbol: J) is a SI derived unit, derived unit of energy in the International System of Units. It is equal to the energy transferred to (or work (physics), work done on) an object when a force of one Newton (unit), newton acts on th ...

s (J) (by
mass–energy equivalence In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular ...
) * 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) * 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 of the . Although have been (base-10) since the , several Chinese measures use (base-16). Local applications have varied, but the usual ...
.

# Comparisons

*1 gram is roughly equal to 1 small paper clip or pen cap. *The Japanese 1 yen coin has a mass of one gram, lighter than the British penny (3.56 g), the
United States cent The United States one-cent coin (symbol: Cent_(currency)#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 a ...
(2.5 g), the
Euro cent The euro (currency symbol, symbol: euro sign, €; ISO 4217, code: EUR) is the official currency of 19 of the Member state of the European Union, member states of the European Union. This group of states is known as the eurozone or euro area ...
(2.30 g), and the 5 cent Australian coins (2.80 g).

*
Conversion of units Conversion or convert may refer to: Arts, entertainment, and media * "Conversion" (''Doctor Who'' audio), an episode of the audio drama ''Cyberman'' * "Conversion" (''Stargate Atlantis''), an episode of the television series * The Conversion (Th ...
*
Duella A duella was an ancient Roman unit of weight In science Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity, awareness, or understanding of someone or something, such as facts ( descrip ...
* Gold gram *
Orders of magnitude (mass) To help compare different orders of magnitude An order of magnitude is an approximation of the logarithm of a value relative to some contextually understood reference value, usually ten, interpreted as the base of the logarithm and the represe ...
*
Gram (Mythology) In Norse mythology Norse mythology is the body of myths of the North Germanic peoples, stemming from Norse paganism and continuing after the Christianization of Scandinavia, and into the Scandinavian folklore of the modern period. The no ...

# References

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