# Bearing Life (Rolling Element Bearing)

The rolling element bearings have a given useful life. Actual lifetime depends on the shaft speed, load, and the type of bearing.

Actual lifetime can be calculated using the equation:

L10h = (16,667/rpm) Ã— (C/P)^{r}

- where L10h is the 90th percentile of life in hours (the point at which only 10% of bearings in identical applications fail) (Note: Average Life = 5 Ã— L10h)
- rpm is the rotational speed of the bearing
- C is the published catalog load rating
- P is the effective load (actual force applied to the bearing)
- r is 3 for ball bearings, or 3 1/3 for other types of rolling element bearings