A method for calculating the molecular volume and surface as the sum of increments of atomic volumes and surfaces is proposed. The calculation of volume and surface increments is performed in three stages: analysis of the intersection picture of interpenetrating spheres; calculation of increments by the exact formulas for atoms with the environment suitable to apply the formulas; and estimation of increments for the remaining atoms by the Monte-Carlo method. At the last stage, the atomic volume increment is estimated using the “network” of elementary spheric volumes which are cone-shaped and have a vertex in the center of the sphere. The atomic surface increment is estimated simultoneously. Volumes and surfaces of some molecules are given in Table 1.