Abstract: In this study, the uncertainties of the optical basicity calculation based on the optical band gap and the refractive index for two glass systems (K2O-Nb2O5-TeO2, B2O3-Na2O-TeO2), have been estimated. The results benefits are very important in the determination of the optical basicity of binary and ternary glass systems. It has been established that as in the binary glass systems, there is a general trend of increasing the oxide ion polarizability with decreasing the oxide optical band gap and increasing the refractive index of the glass samples. Also it has been found that the uncertainty of the optical basicity estimation is around ±5 to ±15%. Some tables have been reported to help us predict the method used to determine the optical basicity for a glass system accurately.