Disclosed herein are improved systems and methods for right sizing grid models for performing, for example, reservoir simulations. Implementations in accordance with the present disclosure may begin with a relatively fine scale grid model. Successive coarsening and resampling operations may be repeated until one or more characteristics of the coarsened grid model begin to unacceptably diverge from those of the fine scale model. Similarly, successive coarsening and upscaling operations may be performed until one or more characteristics of the coarsened grid model begin to unacceptably diverge from those of the previously-coarsened grid model. The resulting coarsened grid model may be suitably sized for reservoir simulations.