SI, CGS, other
usage=Commonly used in cooking and food labeling
millilitreof wateris 1 g at 4 °C.
Typical coins: a euro is 7.5 g and a US penny is 2.5 g
SI conversion=10 dg= 1 g = 0.1 dag = 0.001 kg
imperial conversion=1 g ≈ 0.0353
ounce≈ 0.00220 pound
see also=Orders of magnitude (mass)
:"For other uses of the words gram or gramme, see
The gram (often gramme in
British English), (Greek/Latin root "grámma"); symbol g, is a unit of mass.
Originally defined as "the absolute weight of a volume of pure
waterequal to the cube of the hundredth part of a metre, and at the temperature of melting ice" [ [http://smdsi.quartier-rural.org/histoire/18germ_3.htm Décret relatif aux poids et aux mesures] , 1795] (later 4 °C), a gram is now defined as one one-thousandth of the SIbase 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.
International System of Unitsabbreviation for the gram is g, and follows the numeric value with a space, as in "200 g". [ [http://www.bipm.org/en/si/si_brochure/chapter3/3-2.html SI brochure, Section 3.2] ] [ [http://physics.nist.gov/cuu/Units/rules.html NIST Special Publication 811] ] In some fields and regions, the international standard symbols for units are used quite strictly, in particular in technical and scientific publications and in legally regulated product labels. In other contexts (e.g., grocery market traders), a wide range of other abbreviations can also be encountered, such as gr, gm, grm, gms, grms.
The gram is today the most widely used unit of measurement for non-liquid ingredients in cooking and grocery shopping worldwide. For food products that are typically sold in quantities far less than 1 kg, the unit price is normally given per 100 g.
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.
SI prefixes may not be concatenated (serially linked) within the name or symbol for a unit of measure, SI prefixes are used with the " gram," not the kilogram, which already has a prefix as part of its name. [NIST: "SI prefixes" ( [http://physics.nist.gov/cuu/Units/prefixes.html link to Web site] ). ] For instance, one-millionth of a kilogram is 1 mg (one milligram), not 1 µkg (one microkilogram).SI multiples
note=Common prefixes are in bold face. [Criterion: A combined total of at least 250,000 Google hits on both the U.S. spelling (-gram) and the U.K./International spelling (-gramme). ]
p= | n= | µ= | m= | k=
xM = megagram (
xmc = microgram (mcg)
* When the Greek lowercase “µ” (mu) in the symbol of microgram is typographically unavailable, it is occasionally—although not properly—replaced by Latin lowercase “u”.
* The microgram is often abbreviated “mcg”, particularly in pharmaceutical and nutritional supplement labeling, to avoid confusion since the “µ” prefix is not well recognized outside of technical disciplines. [The practice of using the abbreviation “mcg” rather than the SI symbol “µg” was formally mandated for medical practitioners in 2004 by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) in their [http://www.aapmr.org/hpl/pracguide/jcahosymbols.htm “Do Not Use” List: Abbreviations, Acronyms, and Symbols] because hand-written expressions of “µg” can be confused with “mg”, resulting in a thousand-fold overdosing. The mandate was also adopted by the [http://www.ismp.org/ Institute for Safe Medication Practices.] ] Note however, that the "abbreviation" “mcg”, is also the "symbol" for an obsolete CGS unit of measure known as the “millicentigram,” which is equal to 10 µg.
* The unit name “megagram” is rarely used, and even then, typically only in technical fields in contexts where especially rigorous consistency with the units of measure is desired. For most purposes, the term “
tonne,” or “metric ton” is instead used. Further, whereas unit name “megatonne” or “megaton” (Mt) is often used in popular literature on global climate change, the equivalent value in scientific literature on the subject is the “teragram” (Tg).
*1 grain = 0.06479891 gram
*1 ounce (
avoirdupois) = 28.349523125 grams
*1 ounce (troy) = 31.1034768 grams
*1 gram = 15.4323583529 grains
*1 gram = 89,875,517,870,000
joules (≈9.0 e|13 J/g)
Conversion of units
* [http://nutrition.about.com/gi/dynamic/offsite.htm?zi=1/XJ&sdn=nutrition&zu=http%3A%2F%2Fwww.gourmetsleuth.com%2Fgram_calc.htm grams (weight) conversion to spoons (volume) as used in cooking]
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