How To

How do I measure a bearing?

Deep Groove Bearing Measurement

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It is quite easy to measure bearings providing you follow a few simple steps. The first step is to try and work out if a bearing is manufactured to metric or imperial (inch) measurements. If a bearing is metric as a general rule it will measure in rounded mm. I.e a 6205 bearing is 25mm (id) and 52mm (od) not 24.8 and 51.95. If you are happy that your measurement is accurate and it is indeed not rounding off in mm, then it is likely your bearing is imperial. Imperial bearings are still common in older machines and also equipment manufactured in America. You can measure imperial bearings in metric and then convert to inches using a conversion charts or indeed and online converter which are useful.

You then need to measure the bearing itself. First measure the bore size (id) the the overall or outer diameter (od) then the width. Once you know these three sizes then you can use them to identify the bearing size you require.

If you require any help on identifying a bearing please contact us and we will be more than happy to help.


How do I measure Clearance?

There is a method of measuring the clearance in a bearing after fitting.

Feeler gauges need to be used in the bearing to determine what clearance remains between the bearing outer and the rolling elements. This will be stated generally in the manual for the equipment and not by the bearing manufacturers.


Belt Dimensions

Use the table below to measure belts:

Belt Dimensions









Click a link below to download one of our helpful PDFs:

Codex Ball Bearing Unit General Catalogue And Reference Guide


Koyo Ball Bearing Unit General Catalogue (range, dimensions, loads, speeds etc)


Diamond Infinity Catalogue


Diamond Sapphire Standard Series


Koyo Complete Ball And Roller Bearing Catalogue


Diamond USA Spec


Koyo Imperial Taper Bearings Catalogue

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