What is the dynamic load rating C?

C is the basic dynamic load rating in kN, found in the bearing manufacturer's datasheet. It represents the constant load under which a group of identical bearings would achieve L10 = 1 million revolutions.

What are X and Y load factors?

X is the radial load factor and Y is the axial load factor. Their values depend on the ratio of axial to radial load relative to the threshold e. When Fa/Fr 0.44, X=0.56 and Y=1.4.

Why is the life exponent different for roller bearings?

Ball bearings use p=3 and roller bearings use p=10/3 per ISO 281, reflecting differences in contact geometry (point vs. line contact) and fatigue behavior.

L10 is the basic rating life in millions of revolutions that 90% of a large group of identical bearings will exceed before showing fatigue failure under constant load and speed.

How accurate is this calculator?

This tool uses simplified ISO 281 generic load factors (e=0.44, X=0.56, Y=1.4). For exact results, consult your bearing manufacturer's catalog which provides bearing-specific e, X, and Y values.

Bearing Load Calculator

Name: Bearing Load Calculator
Availability: InStock
Author: Nham Vu

Calculate equivalent dynamic bearing load (P), basic rating life L10, and service life L10h in hours using the ISO 281 approach.

Bearing Parameters

Bearing Type

Dynamic Load Rating, C (kN)

From bearing manufacturer datasheet

Radial Load, Fr (kN)

Axial Load, Fa (kN)

Shaft Speed, n (RPM)

Enter bearing parameters and click Calculate

Results will appear here

Summary

Calculate equivalent dynamic bearing load (P), basic rating life L10, and service life L10h in hours using the ISO 281 approach.

How it works

Pick the bearing type: ball bearing (life exponent p = 3) or roller bearing (p = 10/3).
Enter the basic dynamic load rating C in kN from the bearing manufacturer's datasheet.
Enter the radial load Fr and axial load Fa acting on the bearing, in kN.
Enter the shaft rotational speed n in revolutions per minute (RPM).
The tool applies ISO 281 factors X and Y based on the Fa/Fr ratio vs. the threshold e = 0.44 and computes the equivalent dynamic load P = X·Fr + Y·Fa.
Basic rating life is L10 = (C / P)^p × 10⁶ revolutions; service life in hours is L10h = L10 / (60 · n).

Use cases

Estimate bearing replacement intervals during preventive maintenance planning.
Verify bearing selection against design load and speed requirements.
Compare ball vs. roller bearing life under combined radial and axial loads.
Size bearings for industrial machinery, conveyors, and rotating equipment.
Check whether a chosen SKF, Timken, or NSK bearing meets a target L10h target.

Frequently Asked Questions

Last updated: 2026-06-13 · Reviewed by Nham Vu