Cubic equations of state (EoSs) are the most common type of equations used in petroleum and chemical industries and have many applications including predicting PVT behavior of hydrocarbon mixtures and phase equilibria. They have been developed over time starting from the ideal gas equation. To extend these equations for mixtures, van der Waals mixing rule with Lorentz-Berthelot combining rule is usually used however, the accuracy of the EoSs in prediction still a matter of discussion. The main objective of this study is to apply other combining rules available in the literature to compare between them in their accuracy in predicting the density. Liquid binary and ternary systems, liquefied natural gas mixtures and natural gas mixtures data were collected and used in this study. Codes using MATLAB software were written, validated and used to get the results of this study. Results showed that for liquid binary and ternary systems, the Schmidt and Wenzel EOS has the highest accuracy by applying Hudson-McCoubrey and Fender-Halsey combining rules (0.66%). The Guo and Du and Patel and Teja EoSs had also good results using other combining rules compared to Lorentz-Berthelot. The Schmidt and Wenzel EoS with the conventional combining rule, was the best in predicting the density of the liquefied natural gas mixtures (0.25%) however, Fender-Halsey and Hudson-McCoubrey combining rules in the Guo and Du and Patel and Teja EoSs showed good prediction. Lorentz-Berthelot combining rule is still the best in predicting natural gas mixtures density in the Patel and Teja, Schmidt and Wenzel and Patel-Teja-Valderrama EoSs, however combining rules other than Lorentz-Berthelot are better in the Peng and Robinson family EoSs. The worst combining rule in most EoSs was found to be Waldman-Hagler.