6 min read · 1 Jun 2026 · SLS Engineering Team
How to Read a Bearing Number — A Practical Guide for Engineers
Decode 4-digit, 5-digit and suffix-laden bearing numbers from SKF, NTN and FAG without a catalogue.
The basic structure
Most modern rolling bearings follow ISO 15. A typical number has a type prefix, a series, a bore code, and one or more suffixes for seals, clearance, cage and precision.
Example: 6205-2RS C3
- 6 — deep groove ball bearing
- 2 — light series (62-series)
- 05 — bore code: 05 × 5 = 25 mm bore
- -2RS — contact rubber seals on both sides
- C3 — greater than normal radial internal clearance
Bore code shortcut
For codes ≥ 04, multiply by 5 to get the bore in mm. So 6206 = 30 mm, 6320 = 100 mm.
For 00, 01, 02, 03 the bore is 10, 12, 15, 17 mm respectively.
Common type prefixes
| Prefix | Type |
|---|---|
| 6 | Deep groove ball |
| 7 | Angular contact ball |
| 1, 2 | Self-aligning ball |
| NU, NJ, NUP, N | Cylindrical roller |
| 222, 223 | Spherical roller |
| 302, 303, 320, 322, 323 | Tapered roller |
| 511, 512, 513 | Thrust ball |
Suffix decoder
- ZZ / 2Z — metal shields, both sides
- 2RS / 2RSR / DDU — contact rubber seals, both sides
- K — tapered bore (1:12)
- N — snap-ring groove; NR — with snap ring
- C2 / CN / C3 / C4 / C5 — internal clearance, increasing
- P4 / P5 / P6 — ISO precision class
- /W64 — special grease
Still unsure?
WhatsApp the number to +91 9769116184 with a photo of the housing. Our team cross-references against the SKF, NTN, FAG, Timken and NSK catalogues daily.
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