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How to Identify Bearings by Bearing Number – Calculation and Nomenclature

If you know the Bearing nomenclature procedure and its simple calculations, you can easily identify and decode Bearing details by its Bearing number. This post will discuss how to identify Bearings just from its Bearing Number so that you can easily handle various bearing tasks just by identifying the bearing.

How to Identify Bearings by its Bearing Number

A Bearing number contains many hidden information about the bearing in itself. The bearing no (pattern number) provide us enough details about the bearing silently.

Let us take an example to understand the bearing nomenclature more easily. Suppose, we have a bearing whose patt no is 6305ZZ. Let us divide it in sub components. Here ‘6‘ indicate bearing type. There are few companies which use their separate identifying nomenclature. However, most of them follow a common standard for bearing nomenclature.

Bearing Number Nomenclature

Fig. 1 – Bearing Number Nomenclature

Types of Bearings and Their Code

Types of Bearings and their Codes Fig. 2 – Types of Bearings and their Codes

Thus, we can easily identify now that in case of bearing 6305ZZ, the first digit ‘6 means the bearing type is ‘Single row deep groove ball bearing’.

In case of Inch bearings, the bearing’s first digit will be ‘R’. After ‘R’, the size of the bearing will be given in 1/16th of an inch. To understand it better, Lets take an example of Inch bearing. Suppose, we have R4-3RS bearing. Here, R4 means, it is an inch bearing whose bore size is 4/16th or you can say 1/4th of an inch.

Bearing Series and Their Code in Bearing Number

The second digit of a bearing patter number indicates the bearing series. Series of a bearing denotes the toughness of the bearing. They are:

Decode bearing Number- Series of bearing Fig. 3 – Series (Toughness) of Bearing

Thus, we can identify now that in case of bearing 6305ZZ, the second digit ‘3 means the bearing is of medium toughness.

Bore size of Bearing

The third and fourth digit of bearing patter number indicates the bore size of bearing. It is the inner diameter of the bearing and measured in millimeters. In general, the bore size is equal to five times the third and forth digit of bearing’s patter number. However, from ‘0’ to ‘3’, this formula does not imply. The bore size indicated by ‘0’ to ‘3’ are :

details of bore Size Fig. 4 – Bore size of Bearing

Note : In case there is no fourth digit, then the 3rd digit indicates the bore size in mm. For example: in case of bearing 636, the bore size of the bearing will be 6mm.

Thus, we can identify now that in case of bearing 6305ZZ, the third and fourth digit ‘05’ means the bearing’s bore size is 25 mm.

Shielding/Sealing/Specialty of Bearing

The last letters of the bearing indicates the availability/unavailability/type of shielding or sealing and other specialty in the bearing. The various types of indications are:

Decode bearing - Special Fig. 5 – Sealing/Shielding/Any other details of Bearing

Thus, we can identify now that in case of bearing 6305ZZ, the last letters ‘ZZ’ means the bearing is shielded from both sides.

Coming to the conclusion, we can now easily decode bearing numeric details of most of the bearings. Here, Bearing 6305ZZ means “it is a Single row deep groove ball bearing having medium toughness, with a bore size of 25 mm and is shielded from both sides.

Interesting???? Isn’t it? Its fun to decode bearing number. Try some more bearings pattern no and check how accurate you are.

Our Youtube Channel’s Video on How to Identify Bearings by Bearing Number

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Ratna is a B.E (Computer Science) and has work experience in UK Mainframe IT industry. She is also an active Web Designer. She is an author, editor and core partner at Electricalfundablog.


    • Thanks for your appreciation. These appreciations are very motivating for us. Keep following Many more interesting articles are coming ahead.

  1. Thanks for your support. Our upcoming articles will be even more interesting and informative. We are keen to provide short and crisp information for the technician inside you. Keep following.


    • Hi Ali,
      The different engineering streams are all interrelated and comply each other. We are happy that we could provide you enough data to keep you interested.
      Keep following us.
      Team Electricalfundablog

  2. some information like you shared maybe not correct, like as RS mean one side sealed and 2Rs both side Sealed, i think Rs for Rubber seal and 2RS mean both side of bearing seald with rubber seal.

    • Hi Shafiq,
      Thanks for reaching us out. We will verify the information and correct it if found wrong.
      Appreciate your effort in notifying us. We are always committed to provided our users right and crisp information with no extra and irrelevant content.
      Keep following us. You are an important member of this team.
      Team Electricalfundablog.

  3. thanks so much. this is a very useful information. we use bearings almost everyday.
    Thanks or the information

  4. I have a bearing set one of which has failed.
    The number on the bearing is 6205RSTFP
    Both sides appear to have a metal shield
    Id appears approximately ( I don’t really trust the accuracy of my measurement) 0.980 inches.
    O.D. is approximately 2.050 inches
    width is 0.589 inches
    What do the additional letters ( TFP ) mean?
    Can i get a “6305” bearing for a longer service life, & will it fit in the same bore as the 6205 bearing?
    Thank you for any information.

  5. Thanks a lot dear team, I learn a lot of things about bearings, I am graduate Mechanical Engineer I like all time to get your updates about different topics especially in mechanical fields.
    Before I was confusing about bearings number but now I know very well through your lesson.
    Thanks to all Team.

    Mustapha Abbas Mtulia.

  6. We have updated the Article. Now You can also learn how to identify Bearings by its bearing number through our Video. We request you to Like and subscribe our youtube channel so that you can get relevant videos as soon as we launch.


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