This article presents the implementation of the Chiu, Carratt, and Soong (CCS) gel/glass model in an analytical solution (AS) derived for the free radical polymerization under isothermal condition. This implantation allows AS to be applicable for the whole range of conversion thus making it more useful for practical applications. The results were compared with numerical solution (NS) as well as with experimental data for two different monomers: styrene (St) and methyl methacrylate (MMA). MMA with chain transfer agent was also used for this purpose. The results were found to be in good agreement with both NS and experimental data. NS with and without quasi-steady state assumption were also found to be in good agreement with each other for the entire range of conversion. As constant time step was used, the effect of stiffness on AS during gel effect was visible at low temperature compared to higher temperature. © 2014 American Chemical Society.