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Bearing Bore Size Chart
Bore diameters for the three common deep groove ball bearing series. The last two digits of the part number give the bore.
| Bearing | Bore (mm) | Series |
|---|
Standard: ISO 15 · Data checked: 2026-10-14
Frequently asked questions
How do I read a bearing number like 6204?
The last two digits give the bore in millimetres for bores of 20 mm and above: 04 means 20 mm, 05 means 25 mm, 06 means 30 mm. The digits before indicate the series and type — 6 is the single-row deep groove ball bearing series, and 2 indicates the light 2 series. So 6204 is a light-series deep groove ball bearing with a 20 mm bore.
What is the difference between 6000, 6200 and 6300 series?
Increasing load capacity and outside diameter for the same bore. 6000 is light, 6200 is medium and 6300 is heavy. A 6204 and a 6304 both have a 20 mm bore but the 6304 has a larger outside diameter and can carry more load.
What do the suffixes mean?
They describe seals and clearances — 2RS or 2RSH for rubber seals on both sides, ZZ for metal shields, C3 for a looser internal clearance than standard. Sealed bearings suit dirty environments but run slightly hotter; shielded bearings run cooler but let fine dust in.
Can I substitute C3 clearance for standard?
Only if you know why C3 was specified. C3 is a larger internal clearance, used where the bearing runs hot and the housing or shaft expands, or where a heavy press fit closes up the standard clearance. Using it where standard is specified can let the shaft move axially.