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Ball bearings size chart

Ball Bearing Sizes and Dimensions


Ball bearings are available in all different sizes, depending on the shaft size and requirements of the application. As they are used in all types of industries, they are needed for a large variety of application sizes, from skateboard wheels to oil drills. How are these bearing sizes determined?


How Bearings Are Sized


Bearings are measured by their inner diameter, outer diameter, and width; the size of a bearing is normally listed as such: ID x OD x W. These measurements are normally taken in millimeters, but can be converted to inches. In fact, most manufacturers and suppliers offer bearing measurements in both imperial and metric systems.

Each combination of these measurements corresponds to a series number, usually located directly on the bearing. Ball bearing size charts are widely available, and can be used to find the measurements of a specific bearing. Series 6200 and 6300 are the most commonly used, and typically range from 10 x 30 x 9 mm (.394 x 1.181 x .354 in) to 150 x 320 x 65 mm (5.906 x 12.598 x 2.559 in).


Why So Many Sizes?


As stated before, size depends on the shaft size and application requirements. Bearing size can greatly impact the performance and capabilities of a ball bearing; therefore different sizes are used in different industries.


Generally, smaller ball bearings have more limited load capacities. They are used in applications where space-efficiency is more important than load capacity. Miniature bearings, often constructed as precision ball bearings, are used for extremely small applications, such as medical instrumentation, robotics, or semiconductor equipment. On the other hand, larger bearings have greater load capacities. They are used for heavy-duty industries such as agriculture machinery, mining and drilling equipment, or heavy power tools. Many manufacturers also offer custom bearing size options for very specific applications that have unique requirements.







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How to Measure Ball Bearings


It is not uncommon that the bearing identification number may be illegible or worn completely after long term use, requiring a bearing to be measured manually. This can easily be done using a vernier caliper to easily provide accurate measurements. If this tool is not available, measurements can be taken carefully using a ruler.


  1. First measure the inner diameter by inserting the outside anvils of the caliper into the inner ring of the bearing. Make sure it fits just from edge to edge, and is not tight or applying pressure on the bearing. Or, measure the inner circle of the bearing from end to end with a ruler.
  2. Measure the outer diameter by placing the bearing in the jaws of the caliper until it fits perfectly. Or, measure the bearing from one outside edge to the other using a ruler.
  3. Repeat the last step for the width of the bearing.
  4. Use a bearing size chart to find the bearing series number.


If you are looking for a proper bearing match or replacement, you will also need to pay attention to some other important aspects of the bearing number to find the correct bearing. The suffix can contain a few details about the bearing design and features:


  • Shield or seal type: The bearing may have one or two shields or seals that can be metal, rubber, or snap ring
  • Cage material: The cage can be made of brass, polyamide, steel, or other materials.
  • Internal clearance level: The bearing may require a specific amount of clearance. Usually, C2 means little clearance, no marking means standard clearance, and C3 or higher means larger clearances for bearings operating under high temperatures.
  • Grease temperature: The bearing may require grease with certain temperature capabilities.
  • Outside coatings: The inner or outer ring may be coated with a substance such as aluminum oxide for resistance to certain conditions or environments.


Each manufacturer may use unique suffix codes; it is best to look up a suffix guide to find the correct bearing match or replacement.