The article deals with the problem of increasing the accuracy of machining when milling blanks with end mills. It is shown that as a result of the cutting force of the cutter, elastic depressions of the milling cutter occur, which affects the accuracy of the dimensions obtained. In order to predict the value of the elastic depressions of the milling cutter, it is suggested to take into account the outset of the milling cutter from the chuck and the moment of inertia of the section of the cutting part. As a result of the research, a design model has been constructed to determine the amount of elastic depressions of the end mill. The numerical values of the equivalent diameter of the cutting part of the milling cutter for the most common designs are determined in accordance with GOST.