Abstract: The magnetic interaction of the particles has significant effects on theeffective properties of high-density recording tape. The interaction direct derivation (IDD)estimate based on the single particle's Stoner-Wohlforth model is generalized in thispaper. The generalized IDD (GIDD) estimate, based on micromagnetic theory, is found very close to the results of relatedexperiments and numerical simulations. We show that the IDD (GIDD)estimate has a simple and explicit structure, with clear physicalmeanings for all involvedcomponents, valid for multiphase composites of nonlinear materials, andthe influence of various inclusion distribution can be taken into account.