A newly derived expression for estimation of Gibbs free energy difference (ΔG) between the crystalline and under-cooled liquid of glass-forming alloys have been utilized to obtain theoretical ΔG for a variety of alloy systems. It gives better results nearly overlapping with the experimental values over entire under-cooling region for all alloy systems studied in this paper. However, the theoretical results given by other expressions deviate from the experimental values even in small under-cooling region except that the expressions proposed by Thompson and Spaepen and Lad et al. give a close estimation to the experimental ΔG in the temperature region of 680–937K for Zr41.2Ti13.8Ni10Cu12.5Be22.5 and 450–662K for La55Cu10Ni10Al25, respectively. In addition, the results in present work will provide us with the evidence of the choice of the α values for different metallic glasses.