Estimate L10 bearing life in million revolutions and operating hours from dynamic load rating, equivalent load, and speed.
Enter the dynamic load rating, actual equivalent load, and operating speed to estimate service life.
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Bearing life is one of the most critical parameters in rotating machinery design, since a bearing is almost always the component that determines how long a motor, pump, gearbox, or fan can run before it needs maintenance. The L10 life is the industry-standard way to express this: it is the number of revolutions, or operating hours, that 90% of a population of identical bearings will complete or exceed before the first signs of fatigue failure appear. Only 10% of bearings are statistically expected to fail before reaching the L10 life, which is why manufacturers and reliability teams treat it as the baseline figure for planning replacement intervals.
The calculation depends on two load values: the dynamic load rating C, a fixed value the manufacturer assigns to that specific bearing based on its internal geometry and material, and the equivalent dynamic load P, the actual combined radial and axial load the bearing experiences in service. The ratio of C to P is raised to a power of 3 for ball bearings, or roughly 10/3 for roller bearings, since roller bearings have a different fatigue-load relationship due to their line-contact geometry rather than the point contact of ball bearings.
Continuous-duty estimate. Alongside the raw hours figure, this calculator also converts the life into years assuming the bearing runs continuously (24 hours a day, every day), which is a useful sanity check for planning long-interval maintenance schedules on equipment that runs around the clock, such as process pumps or continuously-running fans.
This calculator is used constantly by mechanical and maintenance engineers when selecting a bearing for a new design, verifying whether an existing bearing is adequately rated for a higher load or speed, or estimating the remaining service interval before a scheduled bearing replacement.
Example: Ball bearing with C = 25,000 N, P = 5,000 N, speed = 1,450 RPM. Load ratio C/P = 5. L10 = 5³ = 125 million revolutions. Bearing Life = (125 × 1,000,000) ÷ (60 × 1,450) ≈ 1,437 hours, or roughly 2 months of continuous 24/7 running. This means 90% of such bearings will run at least this long before fatigue failure.
Reference: The L10 life equation is the standard ISO 281 fatigue-life relationship used across mechanical and maintenance engineering for rolling-element bearing selection. This calculator is for preliminary, educational sizing only and does not account for lubrication, contamination, or temperature-based life adjustment factors used in a full ISO 281 modified life calculation.
L10 life is the number of revolutions or hours at which 10% of a large population of identical bearings, operating under the same load and speed, are statistically expected to show the first signs of fatigue failure. The other 90% are expected to last at least that long, which is why it's used as a conservative baseline for maintenance planning rather than an average failure point.
Ball bearings make point contact with the raceway, while roller bearings make line contact. This difference in contact geometry changes how stress concentrates under load and how fatigue develops over repeated cycles, which is reflected in the load-life exponent: 3 for ball bearings and approximately 10/3 for roller bearings.
The basic dynamic load rating is published by the bearing manufacturer in their catalog or datasheet for that specific bearing designation (e.g. 6205, 22218). It's a fixed value determined by the bearing's internal geometry and material and does not change with your application.
P combines the actual radial and axial loads acting on the bearing into a single equivalent value, typically using manufacturer-supplied factors (P = X·Fr + Y·Fa). For a purely radial load with no significant axial component, P is often simply equal to the radial load Fr — check your bearing's datasheet for the exact combination method.
No — this calculator gives the basic L10 rating life only. A full modified life calculation (L10m or Lnm per ISO 281) also applies reliability, lubrication, and contamination adjustment factors that can significantly increase or decrease the practical service life beyond this basic estimate.