Abstract: An automatic sizing device for particulate or granular material containing small, medium and large sized particles flowing therethrough. The device includes an inclined housing with a first conduit having an inlet opening for receipt of the particulate material, and a second conduit that is located beneath the first conduit and has an outlet for the exit of medium sized particles from the housing. A first mesh sizing screen is longitudinally extended between the inlet and the outlet openings to divide the housing into the first and second conduits and includes a plurality of openings sized to permit passage of only medium and small sized particles therethrough. At least one metering rotor is located in the first conduit adjacent the sizing screen to retard the flow of particulate material through the first conduit and urge the medium and small sized particles to pass through the sizing screen into the second conduit.