Minimum Miscible Pressure (MMP) is a critical parameter in the design of gas injection EOR projects. Several experimental and analytical methods have been proposed in the literature for determining MMP. For example, slim-tube experiments, method of characteristic (MOC) and numerical-simulation/cell-to-cell methods. The majority of these methods have limitations of complexity, long duration and/or high costs. Hence there is a need for alternative approaches. This paper presents a simple method for estimating near-miscibility pressures that is based on a gas-oil interfacial tension calculation procedure. The method assumes near miscibility conditions at low interfacial tensions and relies only on using a cubic equation-of-state (EOS) and the Parchor model. This method enables rapid calculation of MMPs for multiple component gas-oil systems. The method was validated against Zick fluid system and tested in a number of gas-oil systems. We also present a detailed analysis of the quality and compatibility of Whitson characterization with the IFT based method, where we consider a broad range of 12 gas-oil systems, for which PVT (composition, CCE and CV) and gas injection data are available (swelling test, slim tube test). We explore the impact of using swelling test data and slim tube data to tune the EOS on the calculated MMP using IFT based method. The results show that MMP estimation using our IFT based method is fast, easy to implement and reasonably accurate.