Although the increase of suction performance is the primary objective when applying inducers to centrifugal pumps and the combined head of inducer and main impeller is finally to be judged, it is helpful for the designer to estimate the head and flow characteristics provided by the inducer alone in the early design stage. With this knowledge the matching of inducer and pump impeller can possibly be improved and the limiting of operational range that is essentially due to the application of the inducer can be detected in the initial design phase. An already published method (Li, W.-G., 2011. "Head Curve of Noncavitating Inducer". ASME Journal of Fluids Engineering, 133(2)), which was limited to the application on inducers with cylindrical hub and shroud, is extended to work with arbitrary shaped inducer geometries. The paper discusses the method of performance estimation and its implementation in detail. Three different designs based on common guidelines available in the open literature are analyzed with the help of the method described. The predicted head curves are compared to experimental and computational results obtained as part of an earlier study by the authors. Despite the simplicity of the method, good agreement of the head estimations with the experimental and numerical data can be observed. This indicates that the loss model seems to be applicable not only to cylindrical inducers but also to arbitrary-shaped inducers. Investigations of the exit conditions show that the analytical flow model only roughly represents the simulated flow distribution at the inducer outlet.