Considering the wide range of applications of the activated carbon in different applications, the behavior of fluid flow through a packed bed of irregular shaped activated carbon grains has significant importance. Hence, an experimental investigation is conducted on axial-horizontal flow of air and argon through 5 different packed beds of granular activated carbon (GAC) with different grain sizes. Investigations are done different flow line pressure and flow rates. Based on the previous studies, a simple correlation is proposed and results are presented in terms of dimensionless friction factor versus Reynolds number. Results are presented for different grain sizes and the correlation coefficients have been estimated with excellent curve fitting to the experimental data. Outcomes of this study could be used to design the systems in which the pressure drop through a packed bed of GAC is required.