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How to Measure a Bearing When the Number Is Gone

4 min read

Sometimes a failed bearing has no readable number left. The good news: bearings are standardized, so three measurements plus the type are enough to identify almost any of them. You'll need a caliper.

Take three measurements (in mm)

  • Bore (d): the inner diameter — the shaft hole.
  • Outside diameter (D): the outer ring edge to edge.
  • Width (B): the thickness across the bearing.

For example, 25 × 52 × 15 mm is a 6205; 30 × 62 × 16 mm is a 6206. Measure carefully — a millimetre or two changes the answer.

Note the type and build

  • Type: deep-groove ball, angular contact, tapered roller, spherical roller, cylindrical roller, needle.
  • Seals/shields: rubber seals (2RS), metal shields (ZZ), or open.
  • Any visible markings — even a partial number narrows it fast.

Convert dimensions back to a designation

Once you have bore, OD, width and type, a bearing dimension table (or our team) maps them to a designation and the right suffix. Tapered and roller bearings use their own number series, but the same measure-and-match logic applies.

Send us the measurements

Give us the three dimensions, the bearing type and any seal markings — a photo helps — and we'll identify the bearing and quote it across the major brands, new or to a matched equivalent.

Need a part sourced?

Tell us the brand and part number — we source industrial parts from 4,000+ brands and reply with a written quote.

How to Measure a Bearing When the Number Is Gone | AllPartsIn