The chord length distribution is obtained by applying chords in the void space and calculating a histogram of chord lengths. The pore size distribution is computed from the results of a porosimetry simulation on the pore-phase. Porosimetry yields an image with the largest sphere that overlaps a certain voxel. This information, normalised across box dimensions, represents the pore size distribution. The tortuosity factor is calculated as a ratio of the diffusion coefficient of the pore medium to its effective diffusivity. In PoreSpy, the pore phase is converted into an OpenPNM cubic network. The diffusion coefficient is then determined by performing a Fickian diffusion simulation on this orthogonal grid by setting inlet concentration and throat diffusive conductances to 1 and the