In this paper, a methodology is presented to obtain average representative forces exerted by the load inside a tumbling mill on the different faces of the lifters and liners, which are directly related to its power consumption. The methodology is based on the use of virtual sensors included in DEM simulations combined with signal processing and allows obtaining the magnitude of the forces based on the angular position of the lifters as the mill rotates. The methodology is validated by comparing numerical and experimental results obtained from a test bench mill. The variables considered are the power, movement of the load inside the mill, and average forces. The latter are experimentally measured using instrumented lifters specially designed for this task. The results obtained show differences in the magnitude of the average forces in specific angular positions, depending on the operating conditions of the mill. These differences explain the behavior of power consumption with respect to operating conditions reported in the literature.