Quantitative analysis of the mean size of ice crystals is mainly based on heat transfer modelling during the freezing process. So, during this work a standard dairy ice cream was frozen in a freezing device that ensured a uni-directional heat transfer. The temperature profiles inside the frozen ice cream were recorded; these data obtained for different cooling temperatures and for different initial temperatures led to the freezing front rate and the freezing front temperature. Then. these results were interpreted using the Neumann model that allowed to calculate the thermal gradients near the interface in the frozen or in the unfrozen zone. Finally, these results were used to fit empirically the ice crystal mean size as a function of the freezing front rate and of the thermal gradient in the frozen zone. Another type of empirical correlation including the distance to the cooling plate and the Neumann parameter delta was proposed.