Bearing clearance refers to the volume of moving from one limit along the radial or axial direction of a ring to the other limit when another ring is fixed before the bearing is installed. It can be divided into radial clearance and axial clearance according to the moving direction.

The clearance of the roller bearing has been standardized. According to working condition it can be chosen in national standard GB/T4604-2006 and industrial standard JB/T 5389.1-2005 and JB/T 8236-2010. The clearance can be measured according to national standard GB/T25769-2010.

The volume of clearance when the bearing is working (which is called working clearance) have a big influence on the features such as load distribution fatigue lifespan temperature increasement noise and vibration.

The clearance inside the bearing is called "Original Clearance" after the bearing is assembled and before it is installed. The clearance of the bearing when the bearing is working under load is called working clearance.

Because the bearing is influenced by temperature increasement and cooling condition the temperature of the inner ring is comparatively high generally which causes the inner ring to expand larger than the outer ring. Thus clearance becomes smaller. Elastic change will occur at the contact of the rolling element and the raceway when the bearing is working under load which will increase the clearance of the bearing.