Gram

Gram
The mass of this pen cap is about 1 gram
Unit information
Unit system	SI derived unit and CGS base unit
Unit of	Mass
Symbol	g
Unit 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 (alternative British English spelling: gramme;^[1] SI unit symbol: g) (Greek/Latin root grámma) is a metric system unit of mass. Gram can be abbreviated as gm or gr.[1][2]

Originally defined as "the absolute weight of a volume of pure water equal to the cube of the hundredth part of a metre, and at the temperature of melting ice"^[2] (later 4 °C), a gram is now defined as one one-thousandth of the SI base unit, the kilogram, or 1×10⁻³ kg, which itself is defined as being equal to the mass of a physical prototype preserved by the International Bureau of Weights and Measures.

Official SI symbol

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". The SI does not support the use of abbreviations such as "gr" (which is the symbol for grains),^[3]:C-19 "gm" 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.^[4][5] French gramme was taken from the Late Latin term gramma. This word, ultimately from Greek γράμμα "letter" had adopted a specialised meaning in Late Antiquity of "one twenty-fourth part of an ounce" (two oboli),^[6] 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.^[1] There is also evidence that the Greek γράμμα was used in the same sense at around the same time, in the 4th century, and survived in this sense into Medieval Greek,^[8] while the Latin term did not remain current in Medieval Latin and was recovered in Renaissance scholarship.^[2]

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, 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.

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 (3.5274 ounces) 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 (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) = 8.98755179×10¹³ joules (J) (by mass–energy equivalence)
• 1 "eleventh-gram" = 10⁻¹¹ grams in the historic quadrant-eleventh-gram-second system (QES system)

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.^[9] (lighter than the British penny (3.56 g), the United States cent (2.5 g) or the "Euro-cent" (2.30 g)).

See also

• Conversion of units
• Duella
• Gold gram
• Orders of magnitude (mass)

Notes

References

1. ^
2. ^ Décret relatif aux poids et aux mesures, 1795
3. ^ 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 0271-4027. OCLC OCLC 58927093. Retrieved 30 June 2012.
4. ^
5. ^ Convention nationale, décret du 1er août 1793, ed. Duvergier, Collection complète des lois, décrets, ordonnances, règlemens avis du Conseil d'état, publiée sur les éditions officielles du Louvre, vol. 6 (2nd ed. 1834), p. 70. The metre (mètre) on which this definition depends was itself defined as the ten-millionth part of a quarter of Earth's meridian, given in traditional units as 3 pieds, 11.44 lignes (a ligne being the 12th part of an pouce (inch), or the 144th part of a pied.
6. ^ Charlton T. Lewis, Charles Short, A Latin Dictionary s.v. "gramma", 1879
7. ^
8. ^ Henry George Liddell. Robert Scott. A Greek-English Lexicon (revised and augmented edition, Oxford, 1940) s.v. γράμμα, citing the 10th-century work Geoponica and a 4th-century papyrus edited in L. Mitteis, Griechische Urkunden der Papyrussammlung zu Leipzig, vol. i (1906), 62 ii 27.
9. ^

External links

• grams (weight) conversion to spoons (volume) as used in cooking
• Gram at Encyclopædia Britannica