ki·​lo·​gram | \ ˈki-lə-ˌgram How to pronounce kilogram (audio) , ˈkē-lə- How to pronounce kilogram (audio) \

Definition of kilogram

1 : the base unit of mass in the International System of Units that is defined by setting the fixed numerical value of Planck's constant to 6.62607015 x 10–34 joule seconds — see Metric System Table
2 : a unit of force or weight equal to the weight of a kilogram mass under a gravitational attraction equal to that of the earth

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The original concept of the kilogram, as the mass of a cubic decimeter of water (a bit more than a quart), was adopted as the base unit of mass by the new revolutionary government of France in 1793. In 1875, in the Treaty of the Meter, 17 countries, including the U.S., adopted the French kilogram as an international standard. In 1889 a new international standard for the kilogram, a metal bar made of platinum iridium, was agreed to; President Benjamin Harrison officially received the 1-kilogram cylinder for the U.S. in 1890. But no one uses that bar very often; for all practical purposes, a kilogram equals 2.2 pounds.

Examples of kilogram in a Sentence

Recent Examples on the Web The Google Pixel 6, iPhone 13 Pro, and iPhone 12 all have just about 1.00 watts per kilogram of radiation. Caroline Delbert, Popular Mechanics, 26 Apr. 2022 The vertical axis shows best sustained power in watts per kilogram of bodyweight, and the horizontal axis shows altitude ranges from sea level to above 2,000 meters (6,500 feet). Alex Hutchinson, Outside Online, 27 Mar. 2022 One kilogram, just over two pounds, of fentanyl has the potential to kill 500,000 people, according to the Drug Enforcement Administration. Jiovanni Lieggi, Fox News, 12 Mar. 2022 The cost of launching one kilogram, about 2.2 pounds, of payload to outer space has fallen roughly 90 percent in the last 30 years. New York Times, 7 Mar. 2022 The people in the ivermectin group received a dose of 400 micrograms per kilogram for the first three days. Beth Mole, Ars Technica, 31 Mar. 2022 Organic cotton prices skyrocketed to $3.00 per kilogram from $1.70. New York Times, 13 Feb. 2022 Instead of the 11,000 liters of water and 200 square meters of land needed to produce a kilogram of beef, the equivalent amount of cricket food can be produced with just 5 liters of water and 15 square meters of space. Christiaan Hetzner, Fortune, 11 Feb. 2022 So every kilogram of fuel saved on Webb's journey to the Lagrange point could be used to extend its life there. Eric Berger, Ars Technica, 14 Jan. 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'kilogram.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of kilogram

1797, in the meaning defined at sense 1

History and Etymology for kilogram

French kilogramme, from kilo- + gramme gram

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The first known use of kilogram was in 1797

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Last Updated

5 May 2022

Cite this Entry

“Kilogram.” Dictionary, Merriam-Webster, Accessed 16 May. 2022.

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More Definitions for kilogram


ki·​lo·​gram | \ ˈki-lə-ˌgram How to pronounce kilogram (audio) \

Kids Definition of kilogram

: a metric unit of weight equal to 1000 grams


variants: or chiefly British kilogramme \ ˈkil-​ə-​ˌgram How to pronounce kilogram (audio) , ˈkē-​lə-​ How to pronounce kilogram (audio) \

Medical Definition of kilogram

1 : the base unit of mass in the International System of Units that is equal to the mass of a prototype agreed upon by international convention and that is nearly equal to the mass of 1000 cubic centimeters of water at the temperature of its maximum density
2 : a unit of force equal to the weight of a kilogram mass under a gravitational attraction equal to that of the earth

More from Merriam-Webster on kilogram

Nglish: Translation of kilogram for Spanish Speakers

Britannica English: Translation of kilogram for Arabic Speakers Encyclopedia article about kilogram


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