Materials can passivate by forming surface films when placed in aqueous media. However, these films may or may not be stable, and their stability can be predicted by a metric called the Pilling-Bedworth Ratio (PBR). In this article, we extend PBR to predict passivation protectiveness of multi-component materials. We then evaluate this new PBR (ePBR)'s effectiveness by comparing its predictions against experimental studies of 21 multi-element materials of diverse chemistries, with agreement for 17 of the materials. Finally, we encode the methodology to compute ePBR in a web-application to predict the protectiveness of 140,000+ materials in the Materials Project database.