How should a buyer read bore codes 00, 01, 02 and 03 without applying the five-times rule?

LILY Bearing | 2026-10-28

Best answer

Apply the bore table before applying a shortcut

The familiar five-times shortcut has a defined range.

JTEKT's bearing-number table lists 00 as 10 mm, 01 as 12 mm, 02 as 15 mm and 03 as 17 mm. It then identifies the usual 04–96 code range with bores obtained by multiplying the code by five. The table also includes directly expressed and special sizes, which is why the shortcut must not be extended to every designation containing digits. Read the bearing family and the complete manufacturer designation first. A code that is valid in one numbering system does not make an unrelated insert, inch bearing or proprietary assembly follow the same decoding rule.

JTEKT: Bearing number

Check a purchase request with two different cases

For a conventional 6203 designation using this system, the final 03 identifies a 17 mm bore; calculating 3 × 5 would incorrectly produce 15 mm.

For 6205, the conventional 05 code gives 25 mm. Put both the full designation and the verified nominal bore on the inquiry, rather than writing only “03 bearing” or “25 mm bearing.” This creates two independent checks that the supplier can reconcile. If the physical marking has a slash, an unfamiliar prefix or an assembly suffix, consult that product's designation table and drawing. The decoding exercise identifies a nominal size; it does not supply shaft tolerances or authorise a replacement.