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Bearing Life Calculator

ISO 281 L10 life in hours and the dynamic load rating needed for your target.

Calculate rolling bearing rating life from the catalogue dynamic load rating, radial and axial loads, speed and application factor. Ball bearings use exponent 3 and roller bearings 10/3, as defined in ISO 281.

  • Live results
  • Full step-by-step working
  • PASS / FAIL checks
  • Free PDF report

Inputs

From catalogue, e.g. 6306 ≈ 29.6 kN
X = 1, Y = 0 when Fa/Fr ≤ e (catalogue)

Results

Equivalent load P
2400 N
L10
1876 × 10⁶ rev
Life
21564 h
PASS
C required
28.87 kN
Step-by-step calculation (6 steps)
  1. 1Equivalent dynamic load
    FormulaP = fd·(X·Fr + Y·Fa)
    SolutionP = 1.2 × (1 × 2000 + 0 × 0)
    ResultP = 2400 N
  2. 2Load ratio
    FormulaC / P
    Solution29600 / 2400
    ResultC/P = 12.3
  3. 3Basic rating life
    FormulaL10 = (C / P)^p [million revolutions], p = 3
    SolutionL10 = (12.33)^3
    ResultL10 = 1876 × 10⁶ rev
  4. 4Life adjusted for reliability
    FormulaLnm = a₁·L10
    SolutionLnm = 1 × 1876
    ResultLnm = 1876 × 10⁶ rev
  5. 5Life in operating hours
    FormulaLh = Lnm × 10⁶ / (60·n)
    SolutionLh = 1876 × 10⁶ / (60 × 1450)
    ResultLh = 21564 h ≥ 20000 hPASS
  6. 6Dynamic rating needed for target life
    FormulaCreq = P·(60·n·Lh,req / (10⁶·a₁))^(1/p)
    SolutionCreq = 2400 × (60 × 1450 × 20000 / (10⁶ × 1))^(1/3)
    ResultCreq = 28867 N (28.87 kN)

Engineering takeaways

  • Bearing meets the life target. Life scales with (C/P)³, so a 10% load increase cuts ball bearing life by about 25%.
  • Typical life targets: 8 000 to 12 000 h intermittent machines, 20 000 to 30 000 h one-shift continuous, 40 000 to 50 000 h three-shift operation.
  • ISO 281 aISO factor (lubrication, contamination) can raise or lower life considerably. Clean, well-lubricated bearings often exceed L10.

The PDF report contains every input, formula, substitution and check shown above, in LTM calculation-sheet format.

Worked Example

Choose a reliability level to apply the a₁ factor, set a target life in hours, and the calculator tells you whether the bearing passes and what load rating C you would need if it does not.

The calculator above opens with this example. Change any input to run your own case.

Inputs

Bearing typeBall bearing (p = 3)
Basic dynamic load rating C29600 N
Radial load Fr2000 N
Axial load Fa0 N
Radial factor X1
Axial factor Y0
Load (application) factor fd1.2 normal machinery, gear drives
Speed n1450 rpm
Reliability90% (a₁ = 1)
Required life20000 h

Results

Equivalent load P2400 N
L101876 × 10⁶ rev
Life21564 h PASS
C required28.87 kN

Bearing Life Formulas Used

Equivalent dynamic load

P=fd (X Fr+Y Fa)P = f_d\,(X\,F_r + Y\,F_a)
  • X, Yradial and axial factors from catalogue
  • fdapplication load factor

Basic rating life

L10=(CP)p million rev,p=3 ball, 103 rollerL_{10} = \left(\frac{C}{P}\right)^p\ \text{million rev},\quad p = 3\ \text{ball},\ \tfrac{10}{3}\ \text{roller}

Life in hours

Lh=a1 L10×10660 nL_{h} = \frac{a_1\,L_{10}\times 10^6}{60\,n}
  • a₁reliability factor, 1.0 at 90%
  • nspeed (rpm)

Required load rating

Creq=P(60 n Lh,req106 a1)1/pC_{req} = P\left(\frac{60\,n\,L_{h,req}}{10^6\,a_1}\right)^{1/p}

Basis: ISO 281 basic and modified rating life. Results are for preliminary design and should be confirmed against supplier data and the governing standard.

Bearing Life Calculator FAQ

What does L10 life mean?

L10 is the life that 90% of a large group of identical bearings will reach or exceed under the same conditions. Half of the bearings typically last about five times longer.

What life should I design for?

Typical targets: 8 000 to 12 000 hours for intermittent machines, 20 000 to 30 000 hours for one-shift continuous machinery, and 40 000 to 50 000 hours for three-shift plant equipment.

How do I get X and Y factors?

They come from the bearing catalogue and depend on Fa/Fr compared with the factor e. For a deep groove ball bearing with small axial load, X = 1 and Y = 0. With significant axial load, read X and Y from the table for your bearing series.

Why is my bearing failing before L10?

Most early failures come from contamination, poor lubrication, misalignment or incorrect fits rather than fatigue. ISO 281 modified life (aISO) accounts for lubrication and cleanliness and can be much lower than L10 in poor conditions.

How much does load affect life?

Life scales with (C/P)³ for ball bearings, so a 10% load increase cuts life by about 25%, and doubling the load cuts life to one eighth.

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