Minimum miscibility pressure (MMP) is a key parameter determining the feasibility of complete miscibility of oil and gas. Using a slim-tube model, we have experimentally established the MMP for gas and six oil samples. We propose an improved mathematical model for determining the MMP, designed using 97 groups of MMP data for hydrocarbons (18 groups for lean-gas flooding and 79 groups for rich-gas flooding). The model obtained is universal and is a function of the reservoir temperature, the average molecular weight of the C (7+) oil fraction, and the mole fraction of volatile components (CH (4) and N (2) ) and intermediate components (CO (2) , H (2) S, C (2) -C (6) ) in the crude oil and in the injected gas. We compare our proposed model with widely used empirical models, showing considerable convergence between the experimental data and the calculations; the percentage average absolute relative error (%AARE) is 7.11%.