  With the redefinition of the international system of units, the value of the
Planck constant was fixed, similarly to the values of the unperturbed ground
state hyperfine transition frequency of the $^{133}$Cs atom, speed of light in
vacuum. Theoretically and differently from the past, the kilogram is now
explicitly defined as the unit of inertial mass. Experimentally, the kilogram
is realized by atom count or the Kibble balance. We show that only the former
method measures the inertial mass without assuming the universality of free
fall. Therefore, the agreement between the two measures can be interpreted as a
test of the equivalence principle.
