AbstractA flow rate and resistance‐based approach for upscaling of microfiltration processes from lab scale to process scale is presented, in correlation with biopharmaceutical processes. Basic element is the modeling of filtration curves using a resistance‐in‐series model based on the Darcy equation. The influences of the filtration setup and the fouling layer are described as additional resistances that change in course of filtration. The necessary parameters, such as setup resistances and filtration areas, are determined by water flow rate measurements. The model is validated by filtration of a particulate test solution. The presented approach can be used for constant flow and constant pressure driven filtration processes.