The kilogram, symbol \(\pu{kg}\), is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant \(h\) to be \(\pu{6.62607015E-34}\) when expressed in the unit \(\pu{J s}\), which is equal to \(\pu{kg m2 s-1}\), where the metre and the second are defined in terms of c and Δν_Cs.