NS radius R and thickness of the crust l_crust (inset) for the DH and NL3ωρ EOS as a function of the baryon density n_c at the center of the star. Solid black curves indicate the exact solution calculated for the unified EOS (i.e., including the crust EOS), blue curves indicate the radius of the core (above P_cc), and dashed red lines indicate the approximation based on Eq. (11), which were obtained using the core EOS alone.