Cookies on the SKF website

We use cookies to ensure that we give you the best experience on our websites and web applications. By continuing without changing your browser settings, we assume you give your consent to receive cookies. However, you can change your browser cookie setting at any time.

Selecting bearing size using the rating life equations


Three primary methods for calculating bearing rating life are:
  • Basic rating life

    The basic rating life, as defined in ISO 281:2007, is the least complex method of calculating bearing rating life. Its single criterion is subsurface fatigue.
  • SKF rating life

    For modern high quality bearings, the basic rating life determined for a given application can deviate significantly from the actual bearing life. Bearing life in a particular application depends on a variety of influencing factors including lubrication, the degree of contamination, proper installation and other environmental conditions as well as specific bearing design aspects.

    The SKF rating life takes into account the fatigue load limit, the lubrication conditions and solid particle contamination level in the bearings.


The basic rating life method is usually adequate for selecting Y-bearing or Y-bearing unit size, as it is based on experience. In the absence of previous experience regarding requisite life and operational reliability, the guideline values listed in table 1 for the basic rating life L10h can be used.
To fully exploit the life of a Y-bearing or a Y-bearing unit, the modified life equation in accordance with ISO 281:2007 should be used to calculate the SKF rating life or the SKF Generalized Bearing Life Model.
SKF logo