This paper presents a numerical model to study the onset and rate of sand production and compares its predictions against physical-model testing data on Salt Wash South (SWS) sandstone. A reliable sand-prediction tool is essential in sand-production management. It enables engineers to improve well-completion design, with the aim of maximizing well productivity without compromising well integrity. A sanding test on a weakly consolidated sandstone sample was numerically simulated using a finite-difference-based numerical model. The model is based on erosional mechanics in which coupling between fluid flow and mechanical deformation captures some of the key mechanisms that are involved in sand production. Sand is assumed to be produced when the material is fully degraded and hydrodynamic forces are high enough to remove the particles. The outcome of the numerical model shows a reasonable agreement against perforation-test results in terms of the onset and rate of sand production. The model shows that sand production initiates from the perforation tip and propagates to the top and sides of the perforation cavity. The sanding rate increases at higher flow rates. Furthermore, the model predicts external deformations of the sample, which are in close agreement with the experimental observations.