  The Chern number is a genuine topological number. On the other hand, a
symmetry protected topological (SPT) charge is a topological number only when a
symmetry exists. We propose a formula for the SPT charge as a derivative of the
Chern number in terms of the Green function in such a way that it is valid and
related to the associated Hall current even when the symmetry is broken. We
estimate the amount of deviation from the quantized value as a function of the
strength of the broken symmetry. We present two examples. First, we consider
Dirac electrons with the spin-orbit coupling on honeycomb lattice, where the
SPT charges are given by the spin-Chern, valley-Chern and spin-valley-Chern
numbers. Though the spin-Chern charge is not quantized in the presence of the
Rashba coupling, the deviation is estimated to be $10^{-7}$ in the case of
silicene, a silicon cousin of graphene. Second, we analyze the effect of the
mirror-symmetry breaking of the mirror-Chern number in a thin-film of
topological crystalline insulator.
