kilogram, kg 

https://doi.org/10.1351/goldbook.K03391
The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15×10−34 when expressed in the unit J s, which is equal to kgm2s−1, where the metre and the second are defined in terms of c and ΔνCs.
Source:
BIPM, The International System of Units, SI Brochure, 9th ed. (2019), p. 131 [Terms] [Book]
Citation: 'kilogram' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.K03391 RIS BibTex EndNote
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Last revised: January 1, 2021