In Figure , we showed the plot of ln(Cmax/Tmax) versus 1/Tnuc for 17 different combinations of APIs and solvents. The Cmax, Tmax, and the corresponding nucleation temperature during the crystallization of different APIs from their solution and the solvents involved are given in Table . All the experimental values were obtained from literature. From Figure , it is clear that the developed model excellently fits the experimental data irrespective of the APIs and solvents. From Figure and using equation ( ) we calculated the nucleation rate kinetic constant and the Gibbs free energy of nucleation. The calculated kn, G and the corresponding r 2 values are given in Table . In most of the cases the coefficient of determination was always greater than 0.97 which clearly indicates that the proposed model excellently represents the experimental data for all the combination of API/solvent systems considered in this work. The G values typically range from 8 to 62 kJ/mol. These values agree with the G values reported for several organic compounds. Furthermore, we also noticed that there doesn't exist a perfect correlation between the molecular weight and the Gibbs free energy of nucleation. However, the G values are higher for compounds with higher molecular weight. This agrees with the classical nucleation theory which states that the higher the molecular volume tougher in the nucleation. The surface energy calculated according to our model and the classical nucleation theory ranges from 3.779 mJ/m 2 to 49.19 mJ/m 2 . The radius of the critical nucleus of all the APIs studied here was found to be equal ~10 -9 m. Using the size of the critical radius, we mathematically estimated the number of unit cells that constitute the critical nucleus. We assumed this number is equal to the ratio of the cube root of unit cell volume to the diameter of the critical radius (i.e., 2rc). The unit cell volume of the API crystals was obtained from the corresponding crystallographic information file (See Table ). It is clear from Table that the critical nucleus is composed by roughly two to three times the size of the average diameter of the unit cell. We calculated this number by dividing the cube root of the unit cell volume by the diameter of the critical radius. For the combination of APIs/solvents considered in this work, it seems like the critical radius is made by 6 to 15 unit cells. This agrees with the theoretical works of Prado et al who used molecular dynamic simulation to estimate the size of critical radius of a model compound BaS (10.1016/j.commatsci.2019.01.023). This agrees with the experimental study of Nakamura et al., who used in situ TEM to capture the number of unit cells involved during the nucleation process but for the case of crystallisation from amorphous structures. 41 These values are valid only at the studied cooling rates given in Table . Finally, we used our model as in equation ( ) to theoretically estimate two more parameters that are important to homogeneous nucleation, this includes in the number density or the number of molecules formed per unit volume, Nm/V when the time is equal to the induction time tind. According to Kubota, MSZW is assumed to be a point where the accumulated crystals that are grown up to detectable size had reached a fixed value, (Nm/V) when the time t = tind that can be related to the nucleation rate J by the relation: