How to Decode Bearing Part Numbers (and Avoid Buying the Wrong Size) 

Bearing part numbers are more than just product labels. They are a technical language used across industries to identify bearing type, size, and design features. When you understand how to decode these numbers, you can confidently replace bearings, avoid mismatches, and ensure long-term reliability. 

What Do Bearing Part Numbers Mean? 

Bearing numbers are structured codes that reveal key specifications. Whether you're sourcing replacements or choosing bearings for a new application, decoding these numbers helps you match the right product every time. 

Understanding the Structure of a Bearing Code 

Most bearing part numbers follow a consistent format. They typically include: 

• Type code: Indicates the bearing design (e.g., deep groove ball, thrust, roller) 

• Series code: Reflects load capacity and cross-sectional size 

• Bore code: Defines the inner diameter 

• Suffixes: Describe seals, shields, clearances, materials, and other design features 

This structure helps you interpret the bearing’s dimensions and performance characteristics at a glance. A good bearing code guide will help you understand how to read bearing numbers and avoid confusion when comparing options. 

Example: Decoding a Common Bearing Number (e.g., 6205ZZ) 

Let’s break down the bearing number 6205ZZ: 

• 6: Type code for single row deep groove ball bearing 

• 2: Series code for light series 

• 05: Bore code, which means 25 mm (05 × 5 mm) 

• ZZ: Suffix indicating double metal shields 

This bearing is a light-duty, deep groove ball bearing with a 25 mm bore and shields on both sides. Understanding bearing number meaning is essential when selecting replacements or checking compatibility. 

Common Prefixes and Suffixes 

Manufacturers often add prefixes and suffixes to indicate special features. Here are some examples: 

Prefixes: 

• TS2: Heat stabilized up to 160°C 

• W: Stainless steel 

• M: Machined brass cage 

Suffixes: 

• ZZ: Metal shields 

• 2RS: Rubber seals 

• C3: Greater internal clearance 

• P5/P6: Precision ratings 

• 2AS: Special lubrication 

These codes vary by brand, so always consult the manufacturer’s documentation or a bearing reference chart to confirm what each symbol means. 

How Can You Identify Bearing Size from Its Number? 

Understanding bearing size is critical for compatibility. The part number contains clues about the bore, outer diameter, and width. A bearing measurement guide can help you interpret these values correctly. 

Bearing Series and Bore Diameter Explained 

The second digit in the bearing number indicates the series, which affects the bearing’s robustness. The last two digits represent the bore size: 

• 00: 10 mm 

• 01: 12 mm 

• 02: 15 mm 

• 03: 17 mm 

• 04 and above: Multiply by 5 (e.g., 05 = 25 mm) 

This rule helps you quickly determine the inner diameter. You’ll also want to understand bearing series numbers to assess load capacity and fit. 

Using a Bearing Size Chart for Quick Reference 

A bearing size chart allows you to match part numbers with dimensions instantly. These charts list: 

• Bore diameter 

• Outer diameter 

• Width 

• Series type 

You can find comprehensive charts on Online Bearing Store to simplify your selection process. These charts are especially useful for bearing replacement identification when you don’t have the original specs. 

How Tolerances and Fit Impact Bearing Size Selection 

Even small variations in size or clearance can affect performance. For high-speed or precision applications, tolerances matter. Look for suffixes like C3 or P5 to ensure the bearing meets your fit and clearance requirements. These bearing dimension codes are critical for ensuring proper function under load and speed. 

Why Do Bearing Codes Differ Between Manufacturers? 

While many manufacturers follow ISO or ABMA standards, they often include proprietary codes for added features. Knowing how to read bearing numbers across brands helps you avoid mismatches. 

ISO vs. Manufacturer Standards 

ISO standards provide a universal framework for bearing identification. However, brands like SKF, NTN, NSK, and FAG may use unique prefixes or suffixes to indicate: 

• Cage design 

• Lubrication type 

• Heat treatment 

• Material composition 

Understanding these differences helps you interpret cross-brand equivalents. A bearing code guide from each manufacturer can help clarify these variations. 

How to Find Equivalent Bearing Codes 

Use bearing interchange tools or cross-reference charts to match part numbers across brands. For example: 

• SKF 6205ZZ = NSK 6205ZZ = NTN 6205ZZ 

These codes refer to the same bearing type and dimensions, even if the suffixes differ slightly. A bearing reference chart is a helpful tool when switching suppliers or brands. 

Common Mistakes When Comparing Bearing Numbers 

Avoid these pitfalls: 

• Assuming identical dimensions across brands 

• Ignoring suffix differences like clearance or seal type 

• Overlooking manufacturer-specific features 

Always verify the full code before ordering. A bearing measurement guide can help confirm the specs before purchase. 

How to Ensure You’re Buying the Right Bearing Size 

Choosing the correct bearing involves more than matching numbers. You need to confirm dimensions, tolerances, and application requirements. This is where bearing replacement identification becomes essential. 

Verify Bearing Dimensions Before Ordering 

Before purchasing, measure the bearing’s: 

• Inner diameter (bore) 

• Outer diameter 

• Width 

Then compare these to the manufacturer’s specifications or Online Bearing Store listings. Use a bearing size chart to double-check your measurements. 

Cross-Reference Tools and Online Catalogs 

Digital catalogs and lookup tools simplify the process. You can search by part number, dimensions, or application to find compatible bearings quickly. These tools are especially useful when dealing with complex bearing dimension codes. 

When to Contact an Expert for Verification 

If you're unsure about load ratings, speed limits, or fit tolerances, reach out to a bearing specialist. Expert advice ensures your selection meets performance and safety standards. This is especially important when interpreting bearing series numbers or unusual suffixes. 

How Can Online Bearing Store Help You Find the Correct Bearing? 

Online Bearing Store offers tools and support to make bearing identification easy and accurate. Whether you're replacing a part or sourcing for a new project, their resources simplify the process. 

Extensive Product Database with Part Numbers and Specs 

Each product listing includes: 

• Full part number 

• Dimensional details 

• Material and seal type 

• Load and speed ratings 

This transparency helps you compare and select bearings confidently. You’ll also find bearing code guides and bearing reference charts to assist with selection. 

Expert Support for Bearing Selection 

Need help? The Online Bearing Store team provides technical guidance for: 

• Replacements 

• Cross-brand matching 

• Application-specific recommendations 

They’re available to answer questions and verify specifications. Their support is especially helpful when decoding bearing dimension codes or interpreting bearing series numbers. 

Trusted Quality from Leading Manufacturers 

Online Bearing Store sources bearings from top brands like SKF, NTN, NSK, and FAG. You get reliable products backed by industry standards and expert support. Their listings include bearing measurement guides and bearing size charts to help you make informed decisions. 

Explore Our Bearing Size and Number Guide 

Browse the Online Bearing Store catalog to find the right bearing for your needs. Use our bearing number lookup tools and size charts to ensure accurate selection and avoid costly mismatches. 

Frequently Asked Questions 

1. What does the “ZZ” mean in a bearing number?

Itindicates that the bearing has metal shields on both sides to protect against dust and debris. 

2. How do I calculate the bore size from a bearing number?

For codes 04 and above, multiply the last two digits by 5. For example, 05 means25 mm bore. 

3. What is the difference between 6205 and 6205ZZ?

6205 is an open bearing, while 6205ZZ has metal shields on both sides.

4. Can I use a bearing from a different brand if the number matches?

Yes, as long as the specifications are equivalent.Use a cross-reference chart to confirm. 

5. What does the C3 suffix mean?

C3 indicates greater internal clearance, suitable for high-speed or high-temperature applications.

6. How do I measure a bearing manually?

Use calipers to measure the inner diameter, outer diameter, and width. Match these to a bearing size chart.

7. What does the first digit in a bearing numberrepresent?

It identifies the bearing type. For example, 6 means single row deep groove ball bearing. 

8. Are bearing codes standardized across all manufacturers?

Not entirely. Most follow ISO guidelines, but brands may add proprietary prefixes and suffixes.

9. What should I do if Ican'tfind an exact match? 

Use a bearing interchange tool or contact a specialist to find a compatible alternative. 

10. Where can I find a reliable bearing size chart?

VisitOnline Bearing Store for comprehensive charts, bearing code guides, and lookup tools to verify dimensions and codes.