Check the Marking
Look on the bearing ring, shield, seal, packaging or old invoice for the full bearing number and any letters after it.
BMG World Bearing Support
How to Identify a Bearing Number
A bearing number helps identify the type, size and key features of a bearing, but the full marking matters. Before ordering a replacement, check the number, brand, suffixes, seal type, clearance, dimensions and where the bearing was used.
Confirm the Suffix
Suffixes can indicate features such as seals, shields or clearance, but meanings can differ by manufacturer and bearing type.
Measure if Needed
If the marking is worn off, measure the bore, outside diameter and width, then match these against the application and product listing.
Bearing Identification Guide
How to check a bearing number before ordering a replacement
Bearing numbers are useful, but the full reference matters. A replacement should be checked against the visible marking, suffixes, seal or shield type, clearance, dimensions and the machine position before ordering.
Where to find the bearing number
Start by checking the side face of the inner or outer ring, the seal, the shield, the old packaging, the machine manual, a previous invoice or the removed bearing itself. If the marking is dirty or partly hidden, clean it carefully before reading the full reference.
On the bearing Look for numbers and letters stamped, etched or printed on the ring, seal or shield. Photograph the marking before cleaning or disposing of the old part.
On packaging Check the box, sleeve, label or barcode if available. Packaging may show the fuller reference, brand and suffix more clearly than the used bearing.
On machine records Review maintenance notes, drawings, parts lists, previous purchase orders or repair history, especially where the bearing marking is worn or incomplete.
The base number is not always enough
A code such as a bearing series or size may not confirm the seal, shield, clearance, cage, material or application requirement.
Suffixes can change the replacement
Letters after the main number may describe important features. Confirm the suffix against the live product listing before ordering.
Unclear markings need measurement
If the number is unreadable, measure the bore, outside diameter and width, then confirm the machine position and bearing type.
What the numbers and letters can tell you
A bearing designation can include a basic number and additional letters or suffixes. The basic number may point to the bearing type and important dimensions, while the extra letters may describe features such as seals, shields, clearance or other design details. Do not assume every manufacturer uses every suffix in the same way.
1. Bearing type
The main code can help identify whether the part is a ball bearing, roller bearing, needle bearing, tapered roller bearing, thrust bearing or another bearing type.
2. Size reference
The number may relate to the bearing series and size, but avoid calculating or assuming dimensions unless confirmed from the live product details or an official manufacturer source.
3. Seal or shield style
Common examples include codes for shields or rubber seals. Confirm whether the removed bearing is open, shielded or sealed before selecting a replacement.
4. Internal clearance
Clearance markings such as C3 may be shown on some bearings. Match the removed bearing and confirm the application requirement before changing clearance.
5. Brand and equivalent references
Different brands may list equivalent products differently. Use the full bearing reference and application details when checking alternatives.
6. Machine position
The same base number may not be enough if the machine position requires a specific seal, fit, clearance or operating condition. Confirm before ordering.
What if the bearing number is worn off?
If the number is unreadable, do not guess from appearance alone. Measure the bearing carefully and record the application details so the replacement can be checked more accurately.
Bore diameter Measure the inside diameter that fits over the shaft. Use clean measuring tools and record the unit clearly.
Outside diameter Measure the outer diameter that fits into the housing or surrounding component. Check for wear or damage on the old bearing and housing.
Width Measure the bearing width and note whether the removed part includes seals, shields, collars, snap rings, sleeves or other related components.
Application details Record the machine type, shaft position, operating environment, load direction where known, speed range where known and any repeat failure history.
Common suffix examples to check
Suffixes are important because they can separate one variant from another. These are common examples only. Always confirm the exact suffix, brand and live product listing before ordering.
ZZ, Z or 2Z
Often used to indicate metal shields, depending on manufacturer and bearing type. Check whether the removed bearing has shields on one or both sides.
RS, 2RS or similar
Often used to indicate rubber seals or contact seals, depending on the brand. Match the removed bearing where possible and check the live product details.
C3
Commonly used for an internal clearance class greater than normal on many bearing listings. Do not substitute clearance classes without confirming the application requirement.
Other suffixes
Other letters may relate to cage type, snap ring grooves, materials, precision, lubrication or special designs. Confirm against the manufacturer or product listing.
Information to give BMG before ordering
Supplying more detail helps reduce ordering errors, especially when a bearing marking is incomplete or when the same machine position has failed before.
Full marking Send the complete visible bearing number, including any spaces, slashes, hyphens, brand marks and suffixes.
Photos Provide clear photos of the marking, both sides of the bearing, seals or shields, old packaging and the machine position if possible.
Measurements Provide bore diameter, outside diameter and width if the marking is unclear, damaged or missing.
Use case Share the machine type, shaft position, environment, speed or load details where known, and whether the part is a repeat replacement.
Frequently asked questions
Where do I find the bearing number?
Check the side of the inner or outer ring, the seal, the shield, the packaging, machine manual, previous invoice or maintenance record. Clean the part carefully and photograph the marking before disposal.
What do the numbers and letters on a bearing mean?
They can indicate the bearing type, size reference and design features. Extra letters or suffixes may relate to seals, shields, clearance or other details. Meanings can vary by manufacturer, so confirm the full listing before ordering.
What if the bearing number is worn off or unreadable?
Measure the bore diameter, outside diameter and width, then record the machine position, bearing type, seal or shield style and any visible brand or partial marking. Avoid guessing from appearance alone.
How do I measure a bearing if I cannot read the number?
Measure the inside diameter, outside diameter and width using clean measuring tools. Also note whether the bearing is open, sealed, shielded, flanged, housed or supplied with related components.
What do suffixes like ZZ, 2RS and C3 mean?
They are common suffix examples that may point to shields, seals or internal clearance, depending on the manufacturer and bearing type. Always confirm the actual suffix against the live product listing before ordering.
Can the same bearing number have different seals or clearance?
Yes. A base number may appear with different suffixes for seals, shields, clearance or other features. Match the removed bearing where possible and confirm the full code before purchasing a replacement.
What should I give BMG before ordering a replacement bearing?
Provide the full bearing number, brand, suffixes, photos, measurements, machine position and application details. If the marking is incomplete, include bore diameter, outside diameter and width.
Need help matching a replacement bearing?
Keep the old bearing, capture the full marking and confirm the suffix before ordering. If the number is unclear, use measurements and application details to help narrow the correct replacement.