Engineering Reference

L10 life

The bearing life reached or exceeded by 90% of a population under identical conditions.

Definition

L10 is a statistical rating, not a minimum. One bearing in ten is expected to fail before reaching it, which is why critical applications use L5 or L1 and accept a shorter predicted life.

The calculation is L10 = (C ÷ P)p × 106 revolutions, with p = 3 for ball bearings and 10/3 for roller. Because the exponent is 3, halving the load multiplies the life by eight.

Common misuse

Treating L10 as a guaranteed minimum life. It is the 10th percentile, not the floor.

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