Bearing Life Calculator
Enter the bearing's C rating, the actual applied load and RPM to get L10 life — the standard (C/P)³ fatigue calculation for ball bearings.
Last updated: 2026-09-15
How the calculation works
- Bearing fatigue follows (C/P)^k: halve the load and ball bearing life rises 8-fold.
- L10 means 90% of an identical bearing population exceeds that life — it's statistics, not a guarantee.
- Converting to hours uses the operating speed.
Formula
L10 = (C/P)^k × 10⁶ revolutions Hours = L10 × 10⁶ / (60 × RPM)
| Symbol | Meaning | Unit |
|---|---|---|
C | Basic dynamic load rating | N |
P | Equivalent applied load | N |
L10 | Life at 90% survival | million rev |
Worked example
Interpreting the result
The cubic law is the designer's lever: modest load reductions buy enormous life. But the model assumes clean lubrication, correct mounting and alignment — contamination and misalignment dominate real failures. For machine design, target L10 ≥ 30,000 h industrial, 100,000+ h for continuous-duty units.
Assumptions
- Constant radial load; combined loads need the equivalent-load (X/Y) method first.
- Proper lubrication, mounting and alignment.
Limitations
- Does not account for contamination, misalignment, shock loads or vibration damage.
- Axial loads on deep-groove bearings need the X/Y equivalent conversion.
Frequently asked questions
What does L10 life mean?
90% of identical bearings under identical load will exceed that life before fatigue spalling. It's a 90% reliability rating, not a service interval.
How do I extend bearing life?
Reduce load (larger bearing or better alignment), lubricate correctly, keep contamination out, and avoid shock loading. The cubic law means halving load = 8× life.