The present study introduces a new calculation method for obtaining nucleus density formed during nonisothermal crystallization of semicrystalline polymers. Isotactic polypropylene homopolymer (iPP) was used as a semicrystalline model polymer, and its crystalline structure was modified using highly efficient nucleating, Agents or or different cooling rates in order to manipulate the nucleus density (N) within a wide range. The melting and crystallitation characteristics were studied by calorimetry (DSC), and the nucleus density was calculated from the crystallization curves recorded under nonisothermal conditions at a constant cooling rate. The nucleus density was correlated to the optical property, in fact to the haze index of injection-molded plaques in order to qualify the calculated values of N. It was found that N increases more orders Of-Magnitude in nucleated samples and correlates strongly to the optical properties. These observations are according to our expectations and indicate clearly the reliability of the proposed calculation approach.