The article highlights the results of determining the load of a hopper container at operating modes. The features of the container are its floor made up by hatch covers and its angled end walls, due to which the container can be unloaded using the forces of gravity (self-discharging). The calculation of the container strength carried out by the finite element method and included the following stages: determination of longitudinal stiffness, end-wall load, side-wall load, transverse stiffness test, stacking, lifting by upper fittings, and transfer as part of a train. The results of the calculation have shown that the strength of the container at all considered operating modes is provided. The maximal stresses in the container during longitudinal strength testing were 205.3 MPa with the permissible value of 210 MPa. Longitudinal load tests of the container during movement as part of a wagon showed that the maximal stresses in its structure were 165.7 MPa. The conducted studies can be used to make recommendations for designing containers with improved performance, as well as to enhance the efficiency of container transportation.