How to read a bearing number: designations explained
A bearing number looks like a code, but it follows a pattern. Once you know it, you can tell the type, the bore and the main options from the number alone.
The basic number
| Example | Type | Series | Bore code | Bore |
|---|---|---|---|---|
| 6205 | 6 = deep groove ball | 2 = light series | 05 | 25 mm |
| 22212 | 2 = spherical roller | 22 series | 12 | 60 mm |
| 30208 | 3 = tapered roller | 02 series | 08 | 40 mm |
| NU 2310 | NU = cylindrical roller | 23 series | 10 | 50 mm |
Bore code
For bores of 20 mm and above (codes 04 to 96), multiply the last two digits by 5 to get the bore in millimetres. The small bores use special codes:
| Code | 00 | 01 | 02 | 03 |
|---|---|---|---|---|
| Bore | 10 mm | 12 mm | 15 mm | 17 mm |
First digit or letters: the bearing type
| Start of number | Bearing type |
|---|---|
| 1 | Self-aligning ball bearing |
| 2 | Spherical roller bearing |
| 3 | Tapered roller bearing |
| 4 | Double row deep groove ball bearing |
| 5 | Thrust ball bearing |
| 6 | Deep groove ball bearing |
| 7 | Angular contact ball bearing |
| N, NU, NJ, NUP | Cylindrical roller bearing |
| NA | Needle roller bearing |
Common suffixes
| Suffix | Usually means |
|---|---|
| 2RS, 2RS1, 2RSH | Contact seals on both sides |
| 2Z, ZZ | Metal shields on both sides |
| C3, C4 | Radial internal clearance larger than normal |
| K | Tapered bore, 1:12 |
| E | Optimised internal design (manufacturer specific) |
| M | Brass cage (manufacturer specific) |
| P6, P5 | Higher precision class |
Prefixes and suffixes differ between manufacturers. Confirm the meaning in the maker's catalogue before ordering.
Questions
What does 6205-2RS C3 mean?
6 is a deep groove ball bearing, 2 is the light series, 05 gives a 25 mm bore, 2RS means contact seals on both sides, and C3 means larger than normal internal clearance.
How do I find the bore from a bearing number?
For codes 04 to 96, multiply the last two digits of the basic number by 5. Code 00 is 10 mm, 01 is 12 mm, 02 is 15 mm and 03 is 17 mm.
What does C3 mean on a bearing?
C3 is a radial internal clearance larger than normal. It is used where the bearing heats up in service or has a tight fit.
Are bearing numbers the same across brands?
The basic number follows an international pattern, so a 6205 is a 6205 in any brand. Prefixes and suffixes for options can differ, so use a cross-reference for equivalents.