What L10 means
Basic rating life is commonly expressed as the life associated with 90% reliability for a sufficiently large group of apparently identical bearings under defined rating assumptions. The simple relationship uses the dynamic load rating C and equivalent dynamic load P.
The power-law relationship
L₁₀ = (C/P)ᵖ million revolutions, with exponent p = 3 for ball bearings and p = 10/3 for roller bearings in the basic model. Because load is raised to a power, modest changes in equivalent load can strongly change calculated life.
Equivalent load is a design step
The calculator asks for P directly. In a real catalog workflow, P may need to combine radial and axial loads through bearing-type-specific factors and load ratios.
Basic life is not the whole bearing system
Lubrication, contamination, mounting, fits, preload, misalignment, static load, temperature, speed limits, seal friction and stiffness can be just as important as the basic fatigue life number.
Use manufacturer data for release
Bearing manufacturers publish rating methods and factors for their specific products. Use the simple L10 relationship to understand sensitivity and to screen options, then rate the actual bearing with the selected catalog method.
Machine-design verification
Check the full load spectrum, fatigue, lubrication, material data, environment, manufacturing variation and the relevant machine-element standard before release.