A computationally efficient strategy, based on a resistance-in-series and resistance-in-parallel approach, is developed for obtaining diffusivities when nanometer-sized flakes are introduced in a polymer matrix. The mass-transfer resistance is properly defined, and several examples are presented to demonstrate the reliability of this technique. One is also able to determine the optimum configuration to minimize the diffusivity by maximizing the resistance in the polymer matrix. The extent of diffusivity reduction with variables such as the filler loading level and filler geometry is explored and explained. Comparison is also made with a two-dimensional model where the Laplace differential equation is solved using a finite difference method, and agreement with experimental results demonstrates the effectiveness of this technique.