What does kilogram mean?
The kilogram is the SI base unit of mass and is equal to 1,000 grams. It is written in full as kilogram or represented by the symbol kg, and its plural is kilograms. In everyday use, the word appears in recipes, shopping, shipping, sport, and scientific measurement, often with a figure: a two-kilogram bag of flour or a price stated per kilogram. The metric kilogram is slightly more than two pounds, so British and American speakers may use pounds, ounces, or tons alongside it. Although its basic meaning is highly technical, kilogram is ordinary vocabulary in most parts of the world, while the shortened form kilo has a casual tone. In technical engineering, kilogram-force is a related but different unit: it measures force rather than mass. Knowing the distinction prevents confusion, especially when interpreting specifications for pressure, engines, or lifting equipment.
nounThe SI base unit of mass, equal to 1,000 grams. It is represented by the symbol kg.
- A metric unit of mass equal to 1,000 grams.
"The parcel weighs just over two kilograms."
"She bought a kilogram of fresh coffee beans."
"The scientific team recorded the mass as 4.7 kilograms."
The plural adds -s when the word is written in full. The symbol kg remains unchanged.
"The boxes contain several kilograms of equipment."
Since 2019, the kilogram has been defined by a fixed Planck constant rather than by a physical object.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does kilogram come from?
Kilogram entered English through the French kilogramme, formed from the combining form kilo- and gram. The prefix kilo- comes from Greek for “thousand,” while gram derives from Greek gramma, “letter,” a term that came to denote a small unit of weight. The combination reflects the metric relationship between a kilogram and one thousand grams.
How kilogram is actually used
The word has a neutral technical register in measurement and commerce. The shorter form kilo is informal, while kg is the standard SI symbol and is written without a plural.
Easily confused with kilogram
A kilogram measures mass, whereas a kilometre measures distance.