How to Read Bearing Specifications | Bearing Model and Size Interpretation Guide

2026-07-06
Table of Contents

1.Information in Bearing Specifications

Bearing specifications go beyond just the model number; they typically include dimensions, series, material, sealing type, and precision details.

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2.How to Read Bearing Models

Many people see bearing models like 6204, 6308, 22210, or NU205 and think they're just product codes, but these numbers and letters actually represent the bearing type, size series, bore diameter, and even structural design. Different codes mean not only different models but often different applications.

First code or initial digits: Indicates the bearing type.
Common examples：

    Starting with 6 → Deep Groove Ball Bearing
    Starting with 7 → Angular Contact Bearing
    Starting with 2 or 22 → Spherical Roller Bearing
    Starting with NU → Cylindrical Roller Bearing
    T or brand-specific codes → Tapered Roller Bearing



    3.What Size Codes Mean

    Middle codes usually represent:

    • Bearing thickness
    • Outer diameter ratio
    • Load capacity series

    For example：
    6204 vs. 6304

    They may have the same diameter, but:

    6204 → Standard type
    6304 → Thicker, higher load capacity

    Even with the same size, performance differs. Key specs to check：
    Bore diameter (ID) – last two digits、Outer diameter (OD)、Width (thickness)
    Mismatched dimensions mean similar models can't be directly substituted.



    4.Precision and Tolerance Grades

    For high-precision equipment, note：

    • P0 (standard)
    • P5
    • P4

    Different precisions affect both price and application.

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      5.Common Specification Selection Errors

      • Ignoring tolerance fits
      • Focusing only on size, not series
      • Misusing similar substitute models



      6.Finding Alternatives for Mismatched Specs

      Brand codes may vary slightly.
      While NTN, NSK, KOYO, FAG, NACHI, and NMB mostly follow international standards, they may have：

      • Special suffixes
      • Proprietary design codes
      • Alternative model systems

      Cross-referencing is essential.



      Conclusion

      Understanding bearing specifications helps avoid procurement errors and reduces downtime risks. If unsure about your current specs, feel free to provide a model or sample—we can assist with matching.



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