Bearing Clearance Guide

Internal clearance is the play between the rolling elements and the raceways. Choosing the right clearance prevents premature failure.

Clearance grades

Grade	Fit	Application
C2	Tighter than normal	Precision spindles, minimal vibration
CN (C0)	Normal	Standard motors, pumps, fans at normal speeds and temperatures
C3	Greater than normal	Electric motors (especially large frame), higher speeds, warmer operation
C4	Greater than C3	Hot applications, heavy vibration, interference fits on both rings
C5	Loose	Very high temperatures, heavy press fits

When to use C3 clearance

C3 is the most common clearance grade for MRO replacement. Request C3 when:

• The bearing runs at more than 75% of its speed limit
• The shaft has an interference fit (k5, m5, or tighter)
• Operating temperature exceeds 80degC
• The original bearing was C3 (check the old bearing markings)

How to check the old bearing

Look at the suffix on the original bearing. SKF markings: 6205 = CN, 6205/C3 = C3 clearance. FAG markings: 6205.C3. Most brands follow this pattern.

If the old bearing is too damaged to read, default to C3 for motor bearings and CN for general industrial applications.