Solvent diffusion in polymer solutions is one of the main parameters that determine the drying kinetics of polymer films, especially in the concentrated domain. As is well known for polymer/solvent solutions, solvent diffusion coefficients decrease by several orders of magnitude when the solvent concentration decreases. Direct measurements of these coefficients are complex and time-consuming, and most often dedicated to well-characterized "model" systems. In this study, another approach is developed that is based on simple gravimetric experiments coupled with the modelization of the drying kinetics and an optimization iterative procedure. The sensitivity of tire method to various errors (measurement errors and uncertainties on a priori known parameters) is thoroughly investigated. The method accurately estimates diffusion coefficients on a large concentration domain, provided a suitable experimental strategy is used.