In the design or selection of a screw feeder the torque requirement is a principal parameter which is related to the feeder loads, properties of the bulk solid and constructional features of the screw. In this paper the load which is imposed on a screw feeder by the bulk solid in the hopper is assumed to be the flow load determined on the basis of the major consolidation stress. Five boundaries around the bulk material within a pitch are considered and forces acting on these surfaces are analysed. Particular attention is paid to the pressure distribution on the lower region of the screw. An analytical solution for the calculation of torque is determined, which allows the torque characteristics of screw feeders to be predicted. Experimental studies on the required torque for screw feeders are also reported. Two types of material, three troughs with different inside diameter and two screws with different configurations have been investigated. The results from the experiments are presented and compared with the theoretical predictions.