Thickness l_crust (upper panel) and mass M_crust (lower panel) of the crust of a NS for the DH EOS and for different values of n_cc (from top to bottom; 0.16, 0.11, 0.077 fm^-3). The density n_cc = 0.077 fm^-3 corresponds to the crust-core boundary for the DH model. Solid lines indicate the exact results calculated for the complete EOS (including the crust EOS), dashed (red) lines indicate approximations based on Eq. (13) (thickness) and Eq. (19) (mass), dotted (green) lines correspond to linearization Eq. (17) of Eq. (13).