The powder-binder composition in a feedstock used for powder injection molding (PIM) plays a crucial role in manufacturing distortion free products out of sintering. This study successfully demonstrates the application of interparticle spacing parameter, ? to model shape retention (distortion) of a powder injection molded (PIM) feedstocks in sintering. The powders used in the study are Carbonyl iron powder with 2% Ni (CIP), Cobalt based Co-400 (Co-400) and 17-4PH Stainless Steel (SS) alloying composition. Interparticle spacing parameter, ? of CIP, Co-400 and 17-4PH SS powder differing in powder morphology and mean particle size was investigated. The binder system considered for the study is wax-polymer system. The experimental data from this study, suggests the interparticle spacing parameter, ?, proves to be a useful predictor of shape retention of PIM components. The reports in the literature and also based on the experimental data in the present work using Capillary Rheometer and Pycnometer the Interparticle spacing parameter, ? is also a useful predictor of powder-binder separation. An optimum region has been proposed which assists in designing defects and distortion free feedstock formulation right at first time to manufacture components by PIM without resorting to trial-and-error practices currently prevalent in the industry.