Two methods for determining the dependence of the hob teeth wear from the dimensions of the cutting layers are compared. One method is based on the results of modeling the process of gear milling on a conventional milling machine with a tooth-cutter, similar to a hob tooth. The other method is based on mathematical processing the results of calculating the cut of layers and the actual wear of the hob teeth at gears cutting on a gear-cutting machine in accordance with the Gauss - Laplace method.