A guide from Statewide Bearings: What do bearing numbers mean? How to read bearing numbers? These are some of the most common questions when it comes to metal bearings in many industries.
If you’ve ever found yourself wondering “what do the numbers on bearings mean?”, you’re not alone. Bearing codes can be confusing initially, but once you understand the format, they’re actually a very convenient way to identify a bearing’s type, size, and key specifications, giving you key information you need.
This blog aims to help you understand how to read bearings, and how to identify bearing numbers using dimensions such as bore, outer diameter, and width.
The base code of bearing numbers is part of an international designation system that helps engineers, manufacturers, and maintenance professionals quickly identify a bearing’s design and fit. The base codes follow a structured format that reveals the bearing type, series, bore size, and other additional features.
Most standard bearings are identified using a multi-digit number (6205 for example). Once you understand the format, decoding them becomes a straightforward process that saves time and minimises errors when selecting or replacing bearings.
The first digit identifies the bearing type:
Each bearing type is designed for different load conditions. For example, angular contact bearings are ideal for combined radial and axial loads in one direction, while single-row deep groove ball bearings work with lighter radial and axial loads in both directions.
It should be noted that different bearing types, such as roller bearings, may start with a letter (N in this instance) instead of numbers. These prefixes can differ depending on the manufacturer, making it important to look at their catalogue.
The second digit relates to the bearing’s diameter series and toughness.
Choosing the correct series ensures the bearing can accommodate the expected load without excessive size or weight.
The last two digits (except for 00 to 03 as seen below) are multiplied by 5 to get the inner diameter in millimetres:
This standard sizing makes matching or replacing similar bearings across brands and industries very straightforward.
Suffixes in the bearing number give even more detailed information about the bearing’s features. These vary between manufacturers, but some common examples you may see include: