Results of predictions of nodular cast iron density changes during solidification are presented. These changes were calculated by using a mathematical model which bases on a Cellular Automaton - Finite Differences (CA-FD) method. The CA-FD model takes into account, among others, the independent nucleation of graphite and austenite as a function of undercooling, the migration rate of the grains’ borders, non-uniform distribution of temperature and concentration in the calculation domain, diffusion of the carbon in the liquid and the austenite. All simulation were performed at various: nucleation intensity and the eutectic saturation. It has been shown and proofed by other authors that the shrinkage phenomena take place at three stages: pre-eutectic shrinkage, eutectic expansion, and final shrinkage.