The bore code is often the most useful number inside a common metric bearing designation, but it is not the whole dimension table. The Bearing Number Decoder exposes the bore code and bore diameter when the input follows a supported common pattern.
Special bore codes
| Bore code | Common bore diameter | Example |
|---|---|---|
| 00 | 10 mm | 6200 |
| 01 | 12 mm | 6001 |
| 02 | 15 mm | 6202 |
| 03 | 17 mm | 6203-2Z |
Codes 04 through 96
For many common metric rolling bearing designations, bore codes from 04 through 96 are multiplied by five. That makes 04 a 20 mm bore, 05 a 25 mm bore, 06 a 30 mm bore, and 12 a 60 mm bore. The decoder uses that bounded rule for supported families such as 62, 63, NU, 302, and 222 patterns.
Slash bore codes
Some bearing designations use a slash bore format such as 62/22. In that pattern, the number after the slash is read directly as the bore diameter in millimeters. The decoder reports 62/22-2RS as a 62-series deep-groove ball bearing with a 22 mm bore and two rubber seals.
Bore is not full size
A 6205 and a 6305 can share the same 25 mm bore code while belonging to different dimension series. The bore code alone does not tell you outside diameter, width, chamfer, load rating, cage, seal construction, lubricant, or clearance. That is why the output separates bore code from series and keeps the confidence note visible.
Worked examples
| Input | Bore reading | Boundary |
|---|---|---|
| 6206-2RS-C3 | 06 means 30 mm bore. | 2RS and C3 add suffix meanings, not outside diameter. |
| 6312-ZZ | 12 means 60 mm bore. | 63 series and ZZ still require catalog verification. |
| NU205ECP | 05 means 25 mm bore. | ECP is manufacturer-specific. |
| 22212 | 12 means 60 mm bore. | Spherical roller dimensions need exact catalog data. |
Source and limits
Sources: open-source bearing CSV tables from gumyr/cq_warehouse (Apache-2.0), plus NSK bearing designation guidance, JTEKT/Koyo bearing number tables, SKF designation guidance, ISO rolling bearing references including ISO 5753-1 for radial internal clearance, and ANSI/ABMA tapered roller bearing references; verified 2026-08-30.
- This content explains the imported bearing database first, then the parser fallback for supported patterns that are not in the exact table.
- Exact database rows preserve the imported dimensions and suffix notes, but they still do not replace the maker catalog for procurement, maintenance, or safety decisions.
- Bore code parsing does not decide outside diameter, width, cage material, lubrication, fit, load rating, or interchangeability.
- Metric tapered roller and inch-design tapered roller bearings use separate designation systems, so verify the exact catalog entry before purchase or maintenance work.
Related bearing guides
How to Read Bearing Numbers | 6204-2RS-C3 Bearing Number | 30205 and 22212 Bearing Numbers