A new method is described for estimating the particle size distribution of consolidated porous materials using a network model of void structure based on mercury porosimetry. It is compared to the only other comparable method, a modification of that developed by Mayer and Stowe [R.P. Mayer, R.A. Stowe, J. Cell. Sci. 20 (1965) 893] for obtaining the radii of uniform spheres in regular packings. The methods are tested on unconsolidated materials, namely four very different sands, a sample of glass beads of narrow size range and a binary mixture of the coarsest and finest of the sands. The new method compares favourably with the modified Mayer and Stowe technique when estimating the particle sizes of the unmixed sands, and is an improvement for the glass beads and the sand mixture. The network model used to estimate particle size distributions also successfully models the experimental liquid permeabilities of the samples to within one order of magnitude.