A new generalized yield stress scaling equation for electrorheological (ER) fluids was developed by introducing the critical electric field (E-c) and material parameter. This equation can be used to describe the dependency of the yield stress on an electric field not only for conventional ER suspensions with a change in slope from 2.0 to 1.5, but also for giant ER fluids with a change in slope from 2.0 to 1.0. The yield stress data obtained from different ER fluid systems with different material parameters was collapsed onto a single curve for the entire range of electric field strengths using the proper scaling method proposed in this study. (C) 2013 Elsevier Inc. All rights reserved.