<p>Predicting permeability of porous media in saturated and partially saturated conditions is of crucial importance in many geological engineering fields, including water resources management, vadose zone hydrology and contaminant transport modeling. In this study, a capillary bundle model with alternating radii, representing pore bodies and pore throats, is used to develop a model for the permeability of saturated porous media. The proposed model relates permeability to microstructural properties of porous media such as fractal dimension of the pore space, porosity, tortuosity, pore geometry parameters and the critical pore radius (i.e. the maximum pore throat radius). From the proposed model, the influence of pore geometry parameters on permeability is analysed. The proposed model is successfully validated through comparison with published experimental data from 116 different samples and previously published models available in the literature. The proposed model opens up a possibility of estimating the permeability from the critical pore radius, which can be performed by measuring the air entry pressure of porous media. In addition, an empirical relationship was discovered that enables permeability to be determined from porosity and the critical pore throat radius of porous media.</p>