Drawing No. EH–ME–002 // Mechanical Engineering
Bearing Life L10 Calculator
Reviewed August 2026
Estimate basic bearing rating life from dynamic capacity and equivalent dynamic load, and back-calculate the capacity needed for a desired life.
Calculation workflow
Inputs are converted internally to SI, the engineering model is solved, and results are converted back to the selected unit system.
Bearing and load
Life results
Life sensitivity to load (same C and speed)
Worked example
A ball bearing with C = 35 kN and P = 6 kN has a basic life of (35/6)³ ≈ 198.5 million revolutions.
For pure radial loading with X = 1 and Y = 0, P = Fr.
L10 = (C/P)^p million revolutions.
Convert revolutions to hours using rotational speed: L10h = 10⁶L10/(60n).
Background
Basic rating life is a statistical rolling-contact fatigue relationship, not a guarantee of service life.
L10 = (C/P)p million revolutions
Use p = 3 for ball bearings and p = 10/3 for roller bearings.
P = XFr + YFa
X and Y must come from the applicable bearing catalog or design standard. Setting X = 1 and Y = 0 is appropriate only when the bearing/load case permits a pure radial equivalent load.
Frequently asked questions
Practical questions about assumptions, limits and interpretation.
Basic rating life L10 is the life that 90% of a sufficiently large group of identical bearings are expected to equal or exceed under the modeled conditions.
Equivalent dynamic bearing load for combined radial and axial loading depends on bearing type, geometry, contact angle and the Fa/Fr relationship. Use factors from the bearing manufacturer or applicable bearing standard.
The basic rating-life exponent is p = 3 for ball bearings and p = 10/3 for roller bearings.
Basic L10 does not fully represent lubrication quality, contamination, internal clearance, misalignment, temperature or material/fatigue-limit effects. Manufacturer modified-life methods may include additional factors.