Maintenance & Reliability calculator
Ball Bearing Basic Rating Life Calculator
Estimate the basic fatigue rating life of a ball bearing at constant speed. Enter its catalog dynamic rating, calculated equivalent load and required life.
What this calculator does
- Estimate ball bearing basic fatigue rating life from dynamic rating, equivalent load and constant rotational speed.
Formula used
- L10 million revolutions = (dynamic load rating ÷ equivalent dynamic load)^3
- L10 hours = L10 million revolutions × 1000000 ÷ (60 × rpm)
- Rating margin = calculated L10 hours − required L10 hours
Inputs explained
- Basic Dynamic Load Rating: Bearing catalog basic dynamic load rating, C.
- Equivalent Dynamic Bearing Load: Calculated equivalent dynamic load, P, for this bearing arrangement.
- Constant Rotational Speed: Actual constant bearing rotational speed.
- Required Basic Rating Life: Your required basic rating life on the same L10 basis.
How to use the result
- Best suited to ball bearing rating Comparison, Constant-Load fatigue screening.
- This unmodified rating omits lubrication, contamination, mounting and other damage mechanisms. Equivalent load must already include the applicable radial and axial load combination. Static capacity, minimum load and speed limits require separate checks.
Current U.S. benchmarks
- U.S. manufacturing runs at 75.7% of capacity (Federal Reserve, Aug 2026). New factory orders are up 8.5% year over year (Census).
Common questions
- Can I use this equation for roller bearings? No, roller bearings use a different life exponent. This calculator is explicitly limited to ball bearings.
- Is the equivalent load just the shaft weight? Usually not; include all relevant forces and the manufacturer load-combination method. Enter the resulting equivalent dynamic bearing load.
- Does L10 guarantee my bearing survives that long? No, it is a population fatigue rating at 90% survival under stated conditions. Individual bearings and other failure mechanisms can behave differently.
- Can I enter a static load rating as C? No, C is the basic dynamic load rating. The static rating addresses a different failure criterion and cannot replace it.
Last reviewed 2026-10-06.