How do you calculate estimated bearing life?

Multiply the basic rating life by the speed and load factors to get base adjusted life, then multiply by the reliability factor. With 20,000 hr, factors of 1 and 0.75, and a 0.9 reliability factor, base life is 15,000 hr and estimated life is 13,500 hr.

What is L10 bearing life?

L10 is the basic rating life at which 90% of a population of identical bearings survives under rated load — meaning 10% are expected to have failed. The basic rating life input here is your L10 starting point before duty-cycle adjustments.

Why does the reliability factor reduce life?

A reliability factor below 1 reflects the trade for higher survival probability than the standard 90%. Applying 0.9 cuts the 15,000 hr base to 13,500 hr, the life you can expect at the tighter reliability you've specified.

What's a good speed and load factor?

It depends on duty. A load factor of 0.75, as in the example, derates life for loading harsher than the catalog reference; a speed factor of 1 means speed matches the rating basis. Heavier loads and higher speeds push these factors down and shorten life.

Does this account for lubrication and contamination?

No. This model covers speed, load, and reliability only. Lubrication, contamination, and temperature frequently drive real failures and are captured by the ISO 281 life-modification factor — treat this estimate as a baseline, not a guarantee.

How do I extend bearing life?

Reduce load, improve alignment, and keep speed within rating. Beyond the factors here, clean lubrication, proper sealing, and controlled operating temperature usually deliver the biggest real-world gains that this model doesn't capture.

Maintenance & Reliability calculator

Bearing Life Calculator

Bearing life estimates how many operating hours a rolling-element bearing should survive under your actual speed, load, and reliability requirements, starting from the catalog basic rating life (L10). Reliability and maintenance engineers use it to set replacement and inspection intervals instead of running bearings to failure, which protects spindles, gearboxes, and motors from secondary damage. The adjustment factors translate an idealized catalog number into something realistic for your duty cycle. A defensible bearing-life estimate underpins planned maintenance, spare-parts stocking, and root-cause analysis after a premature failure.

What this calculator does

Estimate bearing life from basic rating life and adjustment factors for speed, load, and reliability.
Use it when comparing bearing selections, duty changes, or the effect of reliability targets on expected life.
It takes the catalog basic rating life, scales it by speed and load factors to get an adjusted base life, then applies a reliability factor for the final hours estimate.

Formula used

Base adjusted bearing life = basic rating life × speed factor × load factor
Estimated bearing life = base adjusted bearing life × reliability factor

Inputs explained

Basic rating life: Use the base L10 or catalog life value for the bearing at the reference condition.
Speed factor: Use a factor that reflects the operating speed effect relative to the reference condition.
Load factor: Use a factor that reflects actual bearing load relative to the reference condition.
Reliability factor: Use the reliability adjustment factor required by your standard or target life assumption.

How to use the result

Use it when setting PM intervals or evaluating whether an operating change in speed or load will shorten bearing service life.
It's a multiplicative adjustment model, not a full ISO 281 life calculation — it omits lubrication, contamination, and temperature, which often dominate real bearing failures.

Current U.S. benchmarks

U.S. manufacturing runs at 75.6% of capacity (Federal Reserve, May 2026). New factory orders are up 2.3% year over year (Census).

Common questions

How do you calculate estimated bearing life? Multiply the basic rating life by the speed and load factors to get base adjusted life, then multiply by the reliability factor. With 20,000 hr, factors of 1 and 0.75, and a 0.9 reliability factor, base life is 15,000 hr and estimated life is 13,500 hr.
What is L10 bearing life? L10 is the basic rating life at which 90% of a population of identical bearings survives under rated load — meaning 10% are expected to have failed. The basic rating life input here is your L10 starting point before duty-cycle adjustments.
Why does the reliability factor reduce life? A reliability factor below 1 reflects the trade for higher survival probability than the standard 90%. Applying 0.9 cuts the 15,000 hr base to 13,500 hr, the life you can expect at the tighter reliability you've specified.
What's a good speed and load factor? It depends on duty. A load factor of 0.75, as in the example, derates life for loading harsher than the catalog reference; a speed factor of 1 means speed matches the rating basis. Heavier loads and higher speeds push these factors down and shorten life.
Does this account for lubrication and contamination? No. This model covers speed, load, and reliability only. Lubrication, contamination, and temperature frequently drive real failures and are captured by the ISO 281 life-modification factor — treat this estimate as a baseline, not a guarantee.

Last reviewed 2026-05-12.