How to Read Bearing Specifications | Bearing Model and Size Interpretation Guide
2026-06-10How to Read Bearing Specifications | Bearing Model and Size Interpretation Guide
A﹒Information in Bearing Specifications
Bearing specifications go beyond just the model number; they typically include dimensions, series, material, sealing type, and precision details.
B﹒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
C﹒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.
D﹒Precision and Tolerance Grades
For high-precision equipment, note：
- P0 (standard)
- P5
- P4
Different precisions affect both price and application.
E﹒Common Specification Selection Errors
- Ignoring tolerance fits
- Focusing only on size, not series
- Misusing similar substitute models
F﹒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.
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.
