The following tables list the actual ABEC and RBEC tolerances per ABMA Standard 20. The tables list tolerances for both inner and outer rings, in both inch and metric units. These tables are useful in determining sizes and tolerance for components, such as shafts and housings. The designer should always do a tolerance stack up study at both maximum and least material conditions when sizing components, particularly when designing for miniature ball bearings. Some tolerances have been omitted for clarity. Tolerances for tapered roller bearings can be found in ABMA Standard 19.1 and are not included in these tables