In this paper, a mathematical model is established to estimate the level of polymerization and predict the mechanical properties of the printed materials fabricated by Vat Photopolymerization. The model combines multiple printing process parameters into a single parameter so as to eliminate unnecessary experiments and complicated analysis on each printing process parameters or their correlations. The new model shows better correlations to the achieved mechanical properties of the materials than the prediction model based on overcure ratio and slice thickness. Improved R-squared and significance-F values of linear regression models relating to Ultimate tensile strength and Elastic Modulus of the printed photopolymer proves the reliability of the new parameter Average-Accumulated Normalized Dose A-AND (sigma ohm avg). The new relationship of mechanical properties and A-AND lays foundations for a more robust and direct relationship between printing process parameters and resulting properties of the end products with addition of other printing process parameters. It will in turn minimize the experimental optimization process as well as the material waste.