Bearing Load Calculator
Estimate the L10 bearing life in hours based on radial and axial loads, operating speed, and dynamic load rating. Essential for engineers selecting bearings and predicting maintenance intervals.
Last updated: September 2026
Bearing Life
1,409.96 hours
Formula below · 2 sources (asme.org, Wikipedia) · Updated Sep 2026
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About this calculator
Bearing life is predicted using the ISO 281 standard L10 formula, which estimates the number of hours that 90% of a group of identical bearings will survive. The equivalent dynamic load P is first computed from the radial and axial components with the ISO 281 factors for a deep-groove ball bearing: P = Fr when Fa/Fr ≤ e, otherwise P = 0.56·Fr + Y·Fa. Because e and Y depend on the bearing's static rating C₀, which is not an input, the calculator uses the most conservative values e = 0.19 and Y = 2.30; use your catalogue's X and Y for an exact figure. Then L10 life in hours is: L10 = (C / P)³ × (16,667 / speed), where C is the dynamic load rating (N), P is equivalent load (N), and speed is in RPM. The exponent 3 applies to ball bearings (roller bearings use 10/3). The constant 16,667 converts from millions of revolutions to hours at the given speed. A higher dynamic rating relative to the applied load dramatically extends bearing life — doubling the C/P ratio multiplies life by eight.
How to use
Example: a deep-groove ball bearing has a dynamic load rating C = 20,000 N, radial load = 3,000 N, axial load = 1,000 N, and operates at 1,500 RPM. Step 1 — Fa/Fr = 0.33, above 0.19, so P = 0.56 × 3,000 + 2.30 × 1,000 = 1,680 + 2,300 = 3,980 N. Step 2 — L10 = (20,000 / 3,980)³ × (16,667 / 1,500) = 5.025³ × 11.11 ≈ 126.9 × 11.11 ≈ 1,410 hours. With no axial load, P = 3,000 N and L10 ≈ 3,292 hours. The defaults are this example. A heavier case (5,000 N radial, 2,000 N axial, C = 15,000 N) gives P = 7,400 N and about 93 hours.
Frequently asked questions
What does L10 bearing life mean in practical terms?
L10 life is the number of operating hours after which 10% of a population of identical bearings, running under identical conditions, will have experienced fatigue failure. Stated differently, 90% of bearings will survive beyond this point. It is a statistical estimate based on Hertzian contact fatigue theory, not a guaranteed lifespan for any individual bearing. In practice, proper lubrication, cleanliness, and alignment can extend actual bearing life well beyond the calculated L10 value.
How do radial and axial loads affect bearing life differently?
Radial loads act perpendicular to the shaft axis; axial (thrust) loads act along it. Deep-groove ball bearings can take moderate axial loads, while angular-contact, tapered-roller or thrust bearings are designed for large ones. ISO 281 combines them as P = X·Fr + Y·Fa using factors that depend on bearing type and on the axial load relative to the static rating; this calculator uses the conservative deep-groove values X = 0.56 and Y = 2.30. Because life varies with (C/P)³, a higher P shortens life sharply.
Why does doubling the dynamic load rating C increase bearing life by so much?
Because the L10 formula raises the C/P ratio to the third power for ball bearings, even modest improvements in the load rating yield large life gains. Doubling C increases (C/P)³ by a factor of 2³ = 8, meaning the bearing lasts eight times longer. This non-linear sensitivity means that selecting a slightly larger bearing with a higher C rating is often more cost-effective than frequent replacement. It also explains why overloading a bearing even briefly can cause disproportionately rapid fatigue damage.
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Sources & references
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