kilogram, \(\text{kg}\)
The kilogram, symbol \(\text{kg}\), 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 kg m2 s-1, where the metre and the second are defined in terms of c and ΔνCs.
BIPM, The International System of Units, SI Brochure, 9th ed. (2019), p. 131 (