Apparatus and associated methods relate to determining a fit-quality metric for a mask/face combination based upon a calculated dead-space volume between a virtual mask and a virtual face virtually aligned so as to create an integrity seal circumscribing a mouth and nose region. In an illustrative embodiment, an interactive virtual fitting system may receive a three-dimensional (3D) virtual face associated with a person. The system may retrieve 3D models of various respirators selected by user determined criteria. The system may then compute a fit-quality metric for each of the retrieved 3D models. The potential wearer may then be presented with the metrics for review. The potential wearer may select a respirator based upon these computed metrics. A virtual fitting of many respirators may advantageously reduce the time needed for selecting a properly fitting respirator while simultaneously ensuring that the selected respirator may be comfortable and well fitting.
