How to Read a Bearing Designation
The basic designation
Most rolling bearing designations follow ISO 15 and consist of a basic designation plus optional prefixes and suffixes.
Take 6204 as the example:
| Position | Code | Meaning |
|---|---|---|
| 1st digit | 6 | Bearing type — deep groove ball bearing |
| 2nd digit | 2 | Dimension series — medium duty |
| Last two digits | 04 | Bore code — 04 × 5 = 20 mm bore |
Type codes (first digit)
| Code | Bearing type |
|---|---|
| 0 | Double-row angular contact ball bearing |
| 1 | Self-aligning ball bearing |
| 2 | Spherical roller bearing / thrust spherical roller bearing |
| 3 | Tapered roller bearing |
| 4 | Double-row deep groove ball bearing |
| 5 | Thrust ball bearing |
| 6 | Single-row deep groove ball bearing |
| 7 | Angular contact ball bearing |
| 8 | Cylindrical roller thrust bearing |
| N | Cylindrical roller bearing |
Dimension series (second digit)
For the same bore, a larger series number means a larger outside diameter and width — and higher load ratings:
- 60xx — extra light
- 62xx — light / general purpose (the most common)
- 63xx — medium / heavy duty
Compare the same 20 mm bore: 6004 is 42 mm OD, 6204 is 47 mm OD, and 6304 is 52 mm OD.
Bore codes (last two digits)
| Bore code | Bore diameter |
|---|---|
| 00 | 10 mm |
| 01 | 12 mm |
| 02 | 15 mm |
| 03 | 17 mm |
| 04 and up | code × 5 mm (04 = 20 mm, 10 = 50 mm) |
Common suffixes
| Suffix | Meaning |
|---|---|
| Z / ZZ | Metal shield on one / both sides |
| RS / 2RS | Rubber contact seal on one / both sides |
| /C3 | Internal clearance greater than normal (CN) |
| /C4 | Internal clearance greater than C3 |
| /P5, /P6 | Higher precision class |
| TN9 / MA | Cage material (polyamide / machined brass) |
Note that suffix conventions differ slightly between manufacturers — SKF, NSK, FAG and NTN do not always use identical codes for the same feature. Always check the manufacturer catalog for the exact meaning.
Try it
Pick any designation and look it up in the search or on the Find Specs page — each detail page breaks the designation down into its parts automatically.