Bearing Load Capacity Calculator
Estimate the L10 bearing fatigue life in hours given the dynamic load rating, applied load, and shaft speed. Used by mechanical designers to verify bearing selection and predict maintenance intervals.
About this calculator
Rolling element bearing life is governed by the ISO 281 standard L10 life equation: L10 (revolutions) = (C / P)^p × 10⁶, where C is the basic dynamic load rating (N), P is the equivalent dynamic bearing load (N), and the exponent p = 3 for ball bearings or 10/3 for roller bearings. Converting to hours: L10h = [(C/P)³ × 10⁶] / (n × 60), where n is the rotational speed in RPM. This formula predicts the number of operating hours at which 90% of a large batch of identical bearings will still be running without fatigue failure. The remaining 10% will have failed — hence the '10' in L10. Actual service life depends on lubrication, contamination, and misalignment.
How to use
A ball bearing has a dynamic load rating C = 25,000 N. The applied load P = 5,000 N and the shaft runs at 1,500 RPM. First compute (C/P)³ = (25000/5000)³ = 5³ = 125. Multiply by 10⁶: 125,000,000 revolutions. Convert to hours: 125,000,000 / (1500 × 60) = 125,000,000 / 90,000 ≈ 1,389 hours. Enter C = 25000, P = 5000, and speed = 1500 RPM into the calculator to confirm the L10 life of approximately 1,389 hours.
Frequently asked questions
What does L10 bearing life mean in practical terms?
L10 life is the operating time in hours at which statistically 10% of a large population of identical bearings under identical conditions will have suffered fatigue failure. Equivalently, 90% of bearings are expected to survive beyond this point. It is a reliability benchmark, not a guaranteed individual lifespan. Factors such as poor lubrication, contamination, shock loads, and misalignment can dramatically shorten actual life below the calculated L10 value, so engineers often apply additional life-modifying factors (a₁, a_ISO) to account for these real-world conditions.
How does doubling the applied load affect bearing life?
Bearing life is inversely proportional to the cube of the load ratio (for ball bearings). Doubling the applied load P multiplies (C/P)³ by (1/2)³ = 1/8, reducing L10 life to just one-eighth of its original value. This highly non-linear sensitivity means that even modest overloads significantly shorten bearing life. For example, a bearing with a 1,000-hour L10 life at design load would have only 125 hours of L10 life if the load doubles. Proper load estimation is therefore critical during the design phase.
When should I use a roller bearing exponent instead of the ball bearing exponent?
The load-life exponent p = 3 applies to ball bearings (deep-groove, angular-contact, thrust ball bearings). For line-contact roller bearings — such as cylindrical, tapered, or spherical roller bearings — the exponent is p = 10/3 ≈ 3.33 per ISO 281. Roller bearings have a steeper life-load curve, meaning they are even more sensitive to overload than ball bearings. The choice of bearing type and exponent should match the actual bearing series specified in the manufacturer's catalog to ensure accurate life predictions.