Pressure drop that includes machine pressure drop is essential for design and operation of the multi-compartment bag filter. Effects of the machine pressure drop on the total pressure drop and the filter cloth pressure drop were studied based on the pressure drop model modified with the machine pressure drop. Theoretical equations of initial total pressure drop DeltaP(IN) and final total pressure drop DeltaP(FIN) were derived with the ratio of average filtering velocity of the N-th compartment just before cleaning operation to that of all compartments, m (= (u) over bar (N)/u(av)) and the variance of the filtering velocity in the i-th compartment averaged over the filtering operation (u) over bar to u(av), sigma(2). Simplified correlations without in and sigma(2) for DeltaP(IN) and DeltaP(FIN) were obtained by the comparison of the results of the theoretical pressure drop equations with the numerical solutions. With the simplified correlations, the final total pressure drop, the maximum filtering velocity for the allowable pressure drop, and the pressure drop parameters zeta(d) and alpha were able to be calculated with satisfactory precision for practical use.