Kilogram kg
About the Kilogram
The kilogram is defined by fixing the Planck constant at exactly 6.62607015 × 10⁻³⁴ joule-seconds. Until 20 May 2019 it was the mass of a single platinum-iridium cylinder, the International Prototype Kilogram, approved by the 1st CGPM in 1889 and kept near Paris. It was the last SI unit defined by a physical artefact, and the only base unit whose name carries a prefix.
Related Units
Tonne
t1 t = 1000 kg (exact)
The tonne, or metric ton, is one thousand kilograms, equal to one megagram. It lies between the US short ton of...
Metric carat
ct1 ct = 200 mg (exact)
The metric carat of exactly 200 milligrams is the standard unit for weighing gemstones and pearls. Before...
Pound
lb0.45359237 kg (exact)
The avoirdupois pound is defined as exactly 0.45359237 kilograms. The figure was chosen in the 1959 agreement as a...
Ounce
oz28.349523125 g (exact)
The avoirdupois ounce is one sixteenth of a pound, exactly 28.349523125 grams. It is distinct from the troy ounce of...