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Practical guide to help customers identify part numbers

When you look at a bearing’s box or engraved code, it might seem like a jumble of letters and numbers — but every character has a specific meaning. Learning how to read bearing codes and specifications helps you quickly identify the bearing type, size, clearance, and manufacturer details, ensuring you always get the right part for your machinery.

In this guide, we’ll explain how to read bearing numbers, understand manufacturer part numbers, and make accurate replacements.

1. Understanding Bearing Code Structure

Each bearing has a standardized code that represents its type, series, bore size, and internal design. Most codes follow the ISO or manufacturer-specific pattern, but the structure usually looks like this:

Example: 6205 ZZ C3

Here’s what it means:

• 6 → Bearing Type (Deep Groove Ball Bearing)
  
  

• 2 → Series (Medium Duty)
  
  

• 05 → Bore Size (25mm inner diameter)
  
  

• ZZ → Shield Type (Double Metal Shields)
  
  

• C3 → Internal Clearance

2. Manufacturer Part Numbers (MPNs)

Each manufacturer — such as SKF, NTN, NSK, FAG, Nachi, or Timken — assigns its own part number to identify a bearing model. These part numbers are based on the same ISO system but may include prefixes or suffixes unique to that brand.

For example:

• SKF 6205-2RS1 → Rubber-sealed version
  
  

• NTN 6205ZZ → Metal shielded version
  
  

• NSK 6205DDU → Rubber-sealed version (NSK notation for 2RS)
  
  

Even though they look different, these are all equivalent bearings with the same size and specifications — just from different manufacturers.

✅ Pro Tip: Always check the manufacturer prefix and suffix carefully before ordering. Two bearings with the same core number may have different seals, clearances, or tolerances.

3. Bearing Type (First Digit)

The first digit identifies the type of bearing:

• 1 = Self-Aligning Ball Bearing
  
  

• 2 = Spherical Roller Bearing
  
  

• 3 = Taper Roller Bearing
  
  

• 6 = Deep Groove Ball Bearing
  
  

• 7 = Angular Contact Ball Bearing

4. Bearing Series (Second Digit)

The second digit indicates the series or duty rating (light, medium, or heavy-duty).
This tells you the bearing’s strength, thickness, and load capacity — crucial for choosing the right fit for industrial machinery.

5. Bore Size (Last Two Digits)

The last two digits represent the bore size (inner diameter) in millimeters.

• Multiply by 5 to get the inner diameter (e.g., 05 × 5 = 25mm).
  
  

• Numbers below 04 use special codes (00 = 10mm, 01 = 12mm, etc.).

6. Shield and Seal Type

Common suffixes describe the sealing or shielding:

• Z / ZZ = Metal shield(s)
  
  

• RS / 2RS = Rubber seal(s)
  
  

• Open type = No seal, for lubricated machinery

7. Clearance and Tolerance (Suffix)

The clearance determines how much internal play the bearing has.

• C2 = Less than normal clearance
  
  

• C3 = Greater than normal clearance (common in high-speed applications)
  
  

8. Using Bearing Codes for Replacement

When ordering replacements:

1. Identify the complete code, including prefixes/suffixes.
   
   

2. Match the manufacturer part number (MPN) if available.
   
   

3. Confirm bore size, series, and clearance

If you’re unsure, provide your supplier with the old bearing’s code or a clear photo, and they can cross-reference the exact match.

Conclusion

Knowing how to read bearing codes and manufacturer part numbers saves you time, prevents costly mistakes, and ensures you always order the correct replacement. Whether you’re working on industrial machinery or motor applications, understanding these specifications guarantees performance and reliability.