This Design Guide presents a calculation method for applying the most recent life rating procedure for ball and roller bearings, ""Rolling Bearings - Dynamic Load Ratings and Rating Life,"" published by the International Standards Organization (ISO 281/2). It incorporates the latest developments in bearing technology and presents them in a straightforward manner. It includes both surface and subsurface failure modes and the effects on bearing life of material, residual stress, lubrication and contamination in addition to applied loading. The calculation method is the result of extensive investigation and collaboration between bearing manufacturers and users throughout the world and is intended to provide a common procedure for all bearing practitioners to calculate bearing life on a consistent basis. It defines the generalized bearing stress field and material strength parameters for both oil and grease lubricated applications.It addresses the effects of lubricant properties and the modes of operation in elastohydrodynamic and boundary lubrication regimes. It recognizes the interdependence of all these parameters and calculates a single integrated stress-life factor from the generalized stress field.A computer program called ASMELife is included with the design guide to perform the calculations. The procedure has been successfully correlated with numerous data sets over a wide range of applications for all common types of ball and roller bearings.