Editing Gram (section)

{{Short description|Metric unit of mass}}
{{About|the unit of mass||Gram (disambiguation)|and|Grams (disambiguation)}}
{{Redirect|Gramme}}
{{Use dmy dates |date=July 2020}}
{{Infobox unit
| name          = gram
| image         = [[File:One-yen coin mass.jpg|300px]]
| caption       = The mass of this Japanese [[one yen coin]] is 1.00 gram. A [[weight scale]] such as this can give an accurate reading of mass for many objects (see [[Weight vs. mass]]).
| standard      = [[SI]]
| quantity      = [[Mass]]
| symbol        = g
| namedafter    = 
| units1        = [[SI base unit]]s
| inunits1      = 10<sup>−3</sup> [[kilogram]]s
| units2        = [[CGS unit]]s
| inunits2      = 1 gram
| units3        = [[Imperial units]]<br/>[[United States customary units|U.S. customary]]
| inunits3      = {{convert|1.000000|g|oz|disp=out|lk=out|abbr=off}}
| units4        = [[Atomic mass unit]]s
| inunits4      = {{val|6.02214076|e=23|u=[[Dalton (unit) | Da]]}}
}}
The '''gram''' (originally '''gramme''';<ref>{{cite web |url = http://www.statutelaw.gov.uk/content.aspx?activeTextDocId=2191980 |title = Weights and Measures Act 1985 (c. 72) |work = The UK Statute Law Database |publisher = Office of Public Sector Information |quote = §92. |access-date = 2011-01-26 |url-status = live |archive-url = https://web.archive.org/web/20080912105635/http://www.statutelaw.gov.uk/content.aspx?activeTextDocId=2191980 |archive-date = 2008-09-12 }}</ref> [[SI]] unit symbol '''g''') is a [[Physical unit|unit]] of [[mass]] in the [[International System of Units]] (SI) equal to one thousandth of a [[kilogram]].

Originally defined in 1795 as "the absolute [[weight]] of a [[volume]] of pure [[water]] equal to [[Cube (algebra)|the cube]] of the hundredth part of a [[metre]] [1 [[Cubic centimetre|cm<sup>3</sup>]]&#93;, and at [[Melting point of water|the temperature]] of [[Melting point|melting]] [[ice]]",<ref>{{cite web |url=http://smdsi.quartier-rural.org/histoire/18germ_3.htm |title=Décret relatif aux poids et aux mesures |language=fr |archive-url=https://web.archive.org/web/20130225163152/http://smdsi.quartier-rural.org/histoire/18germ_3.htm |archive-date=2013-02-25 |year=1795 }}</ref> the defining temperature (≈0&nbsp;°C) was later changed to 4&nbsp;°C, the temperature of maximum density of water.

By the late 19th century, there was an effort to make the [[Base unit (measurement)|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 {{val|1e-3|u=kg}}). The kilogram, [[2019 revision of the SI|as of 2019]], is defined by the [[International Bureau of Weights and Measures]] from the fixed numerical value of the [[Planck constant]] ({{mvar|h}}).<ref name="draft-resolution-A">
{{citation
 |title=Draft Resolution A "On the revision of the International System of units (SI)" to be submitted to the CGPM at its 26th meeting (2018)
 |url=https://www.bipm.org/utils/en/pdf/CGPM/Draft-Resolution-A-EN.pdf
 |access-date=17 May 2020
 |archive-date=29 April 2018
 |archive-url=https://web.archive.org/web/20180429025229/https://www.bipm.org/utils/en/pdf/CGPM/Draft-Resolution-A-EN.pdf
 |url-status=dead
}}</ref><ref>[http://www.bipm.org/en/committees/cipm/meeting/105.html Decision CIPM/105-13 (October 2016)] {{Webarchive|url=https://web.archive.org/web/20170824095943/http://www.bipm.org/en/committees/cipm/meeting/105.html |date=24 August 2017 }}.  The day is the 144th anniversary of the [[Metre Convention]].</ref>