The mass of this pen cap is about 1 gram
|Unit system||SI derived unit|
|1 g in ...||... is equal to ...|
|SI base units||10−3 kilograms|
|CGS units||1 gram|
|U.S. customary||0.0353 ounces|
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" (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.
Symbol and abbreviations
The International System of Units (SI) unit symbol for the gram is "g" following the numeric value with a space, as in "640 g". It is not "gr" (which is the symbol for grains),:C-19 "gm" (easily mistaken for "mg", milligrams) or "Gm" (giga-metre).
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 gramma. This word, ultimately from Greek γράμμα "letter" had adopted a specialized 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 Late Latin poem de ponderibus et mensuris ("of weights and measures" (c. 4th century) — the title of which is also reflected in the French poids et mesures ("weights and mesures") in the title of the 1795 decree, Décret relatif aux poids et aux mesures (and indirectly in the name of the General Conference on Weights and Measures responsible for the modern definition of the metric units). There is also evidence that the Greek γράμμα was used in the same sense at around the same time (4th century), and it survived in this sense into Medieval Greek, while the Latin term did not remain current in Medieval Latin, and was recovered in Renaissance scholarship, when the poem was received as a work of the 1st-century grammarian Remmius Palaemon.
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.
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.
- 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)
- 1 gram (g) = 5 carats (ct)
- 1 gram (g) = 8.98755179×1013 joules (J) (by mass–energy equivalence)
- 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 (2.5 g) or the "Euro-cent" (2.30 g)).
- "Weights and Measures Act 1985 (c. 72)". The UK Statute Law Database. Office of Public Sector Information. Retrieved 2011-01-26.
- Décret relatif aux poids et aux mesures, 1795
- 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 58927093. Retrieved 30 June 2012.
- "Décret relatif aux poids et aux mesures du 18 germinal an 3 (7 avril 1795)" [Decree of 18 Germinal, year III (April 7, 1795) regarding weights and measures]. Grandes lois de la République (in French). Digithèque de matériaux juridiques et politiques, Université de Perpignan. Retrieved November 3, 2011.
- 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.
- Charlton T. Lewis, Charles Short, A Latin Dictionary s.v. "gramma", 1879
- 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.
- first edited in 1528 by Johann Setzer of Hagenau, together with works by Celsius, Priscian and Johannes Caesarius; Aurelij Cornelij Celsi, De re medica, libri octo eruditissimi. Q. Sereni Samonici Praecepta medica, uersibus hexametris. Q. Rhemnij Fannij Palaemonis, De ponderibus [et] mensuris, liber rarus [et] utilissimus
- "Circulating Coin Designs". Japan Mint. Retrieved 7 March 2010.