The Vmax™ technique has been used extensively to estimate filter area requirements for normal flow filtration (NFF) processes in biopharmaceutical applications. The benefits that this technique presents over conventional flow decay methods are the speed of testing, reduced volume requirements for evaluation, and competitive testing of varying filter types/sizes — all of which present an optimized filter screening strategy and preliminary estimate of optimized filter size requirements. Filter size or filtration area requirements derived using the Vmax technique consist of contributions from both capacity and flow-time aspects of the filtration process. This article examines the relative contributions of these terms to overall filter sizing vis-à-vis the ease of fluid filterability…