A method for calculating a control parameter used to control a discharge amount of powders in a powder and/or granule feeding apparatus including a hopper into which powders are charged, and a feeder that conveys the powders from the hopper by a screw and discharges the powders outside the apparatus, comprising:
- filling the powders into the feeder without creating any non-filled area by conveying the powders at a predetermined speed within the feeder, the powders are first charged at a beginning of operation;
- bringing the powders into a consolidation state within the feeder by conveying the filled powders through the feeder at a speed faster than the predetermined speed;
- and
- calculating the control parameter using the discharge amount of the powders in the consolidation state.