We present an efficient numerical method to calculate shape truncation functions for Wigner-Seitz atomic polyhedra in crystalline solids. We apply our method to the case of simple cubic (SC), face centered cubic (FCC) and body centered cubic (BCC) lattices. A straightforward comparison of our results and of those obtained by other numerical techniques with the exact ones, analytically known in some simple cases, shows the efficiency and high accuracy of our method.