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kilogram, abbr. kg, fundamental unit of mass in the metric system, defined as the mass of the International Prototype Kilogram, a platinum-iridium cylinder kept at Sèvres, France, near Paris. Copies of this standard are deposited at bureaus of standards throughout the world, and other units of mass are defined in terms of it. When the metric system was originally devised, the kilogram was defined so that 1,000 cubic centimeters (1 cubic decimeter) of pure water has a mass of exactly 1 kilogram.
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(kil -ŏ-gram) Symbol: kg. The SI unit of mass. It is defined as the mass of a prototype platinum-iridium cylinder kept at the International Bureau of Weights and Measures at Sèvres, France. See also solar mass.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a unit of mass; one of the seven basic units of the International System of Units (SI). It is equal to the mass of the International Prototype Kilogram, kept at the International Bureau of Weights and Measures. Its abbreviated designations are as follows: Russian, kg; international, kg.

In the 18th century, when the metric unit system was first introduced, a kilogram was defined as the mass of 1 cubic decimeter (dm3) of water at 4°C (the temperature of highest density). However, the mass of the prototype kilogram (a cylindrical platinum weight made in 1799) was found to be about 0.028 g greater than the mass of 1 dm3 of water. In 1889 the currently existing definition of a kilogram was accepted, and a weight designated by the symbol Κ (German capital K) was approved as the International Prototype Kilogram. It is made from a platinum-iridium alloy (10 percent Ir) and has the shape of a cylinder 39 mm in diameter and 39 mm high. Of the 40 copies of this prototype that were made, two (nos. 12 and 26) were turned over to Russia. Standard no. 12 is accepted in the USSR as the primary government standard of mass; standard no. 26 is a copy of the primary standard.

For a long time no distinction was made between the mass and weight of bodies. Thus, a kilogram served as a unit not only of mass but also of weight (the force of gravity). Differentiation between units of mass and weight was established at the Third General Conference of Weights amd Measures (1901). A decision of the conference emphasized that the weight of a body is equal to the product of its mass and free-fall acceleration and introduced the concept of normal weight and normal gravitational acceleration (980.665 cm/sec2). A separate unit of force and weight—the kilogram-force—was established at that time. The same principle is preserved in the International System of Units, where the newton has been adopted as the unit for measurements of force.

Designations for multiples and fractions of a kilogram are formed by adding a prefix to the designation “gram,” such as megagram (Mg) and milligram (mg). Although a kilogram is not one of the units that can be defined by invariable natural constants (that is, the prototype standard for a kilogram is not reproducible), its accuracy satisfies the requirements of modern science and engineering (the relative error in comparisons with the prototype does not exceed 2 X 10-9).


Smirnova, N. A. Edinitsy izmerenii massy i vesa ν Mezhdunarodnoi sisteme edinits. Moscow, 1966.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


The unit of mass in the meter-kilogram-second system, equal to the mass of the international prototype kilogram stored at Sèvres, France. Abbreviated kg.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


The International Standard unit for mass; equals 1000 grams.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.


1. one thousand grams
2. the basic SI unit of mass, equal to the mass of the international prototype held by the Bureau International des Poids et Mesures. One kilogram is equivalent to 2.204 62 pounds.
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

metric system

A system of weights and measures that uses the gram, meter and liter as its primary units of weight, distance and capacity. The metric system is used all over the world except in the U.S., Liberia and Myanmar (formerly Burma). See space/time.


 milligram (1/1000) .0000022
 gram               .0022      .04
 decagram   (10)    .0220      .35
 hectogram (100)    .2204     3.5
 kilogram (1000)   2.2046    35.3


 1      =  1.06 quarts
 3.8    =  1 gallon

 Meters      Feet

 1 decameter   (10 m)      33
 1 hectometer (100 m)      328
 1 kilometer (1000 m)     3281

 Meters          Inches

 1 meter         39.37
 1 centimeter      .3937
 1 millimeter      .03937
 1 micrometer      .00003937
 1 nanometer       .00000003937

Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
References in periodicals archive ?
In conclusion, we have succeeded in developing a sensitive and rapid SRED/CAM DNase I assay method that is convenient and reliable for determining picograms to femtograms of DNase I in 1-[micro]L serum samples within 30 min.
The report urges the government to launch an investigation if dioxin concentration in soil is found to exceed 250 picograms per gram.
The PicoPLEX-WGA Kits amplify single copy genomic DNA with input concentrations as low as 15 picograms to yield a highly reproducible library from a single cell.
We express body burdens in terms of picograms of dioxin TEQs per gram body lipid or parts per trillion TEQ lipid; these compounds are known to accumulate in lipid, and TEQ concentrations in mother's milk, blood, and other organs are often expressed on a lipid basis.
Vertebrate sex steroid concentrations in peripheral plasma typically fall in the picogram to low nanogram range (between 1 x [10.sup.-12] and 1 x [10.sup.-9] g/mL) (35).
The government has set the maximum tolerable dioxin levels at 1 picogram of dioxins per liter of water and 1,000 picograms per gram of soil (1 picogram is a trillionth of a gram).
TV Asahi said the dioxin concentration in vegetables, including spinach, produced in Tokorozawa was 0.64-3.8 picogram per gram.
The Los Alamos flow cytometer yields results with a much lower uncertainty (2-5% versus 10% for PFGE), is 200,000 times more sensitive than PFGE, and uses picogram quantities of DNA, as opposed to the hundreds of nanograms called for in PFGE.
The survey also found that the annual average level of airborne dioxin in Otaru, Hokkaido, and four other locations surpassed the agency's allowed maximum average of 0.8 picogram per cubic meter.
The person with the highest dioxin intake had a TDI level of 8.6 picograms while the person with the lowest had 0.45 picogram.
Ten weeks ago, EPA's science advisory board recommended the agency continue to view a daily dioxin dose of 0.006 picogram per kilogram (pg/kg) of body weight as posing a one-in-a-million lifetime increased risk of developing cancer, says Silbergeld, an advisory board member.
(A femptogram is 10.sup.-15 gram.) Assuming his 50-kilogram wife inhaled 20 cubic meters of air daily, he calculated a daily dose for her of 0.02 picogram (a picogram is 10.sup.-12 gram) per kg of body weight per day -- well below the 1 to 5 pg/kg body weight that he says is being discussed by some scientists as a possible "allowable daily intake" value for TCDD.