Multicomponent gas mixtures of precisely known compositions are crucial for engineering process design and optimization of wide range of applications. The standard methods to produce them by accurately weighing the gases or by the controlled flow of gases are cumbersome, expensive and time-consuming. We develop a simple, highly scalable and low-cost gas mixing system in which desired gas mixture compositions are predicted and generated using the densities of pure gas components determined a priori from the components' mole fraction. Pure gas densities are uniquely correlated with the experimentally measured pressure and temperature using the thermodynamic equation of states of real gases. The developed gas mixing system is validated by analyzing five quaternary and four ternary gas mixture compositions containing different fractions of Ar, CO2, CO, CH4, N-2, and H-2 predicted and generated by the system, using a calibrated gas chromatograph. (C) 2013 Elsevier B.V. All rights reserved.