The particle and void sizes distributions of the soil are related with the assumption that a voidconstant relationship at all di§erent scales and a relationship between pore and particle size ofa given packing. In the relationship between pore and particle sizes, a particle elongation factoris applied based on the Arya and Paris model. A áow trajectory tortuosity factor based on theFuentes model can also be applied. Since the void size distribution is associated to the soil waterretention curve, the proposed relationship can be used to estimate this curve from particle sizedistribution.