Short answer: to find a bearing, measure its bore (d), outer diameter (D) and width (B) in millimetres with a caliper, then find d x D x B in the table below. The table lists every ball bearing size Precispin stocks, from 2 x 5 x 2 mm to 35 x 62 x 9 mm, with links to each bearing.
How do I measure a bearing?
- Clean it and use a caliper, ideally digital with 0.01 mm resolution.
- Bore (d): measure the inside of the inner ring with the inside jaws.
- Outer diameter (D): measure across the outer ring with the outside jaws.
- Width (B): measure across the rings, not the shield. On a flanged bearing measure the width without the flange and note the flange diameter and thickness separately.
- Round to the nearest standard value (miniature sizes come in 0.5 mm steps) and look it up below.
If the bearing is in inches (for example R-series), convert by dividing millimetres by 25.4 and check the code instead.
How do I read the bearing number?
For 6xx miniature bearings the last digit is the bore in millimetres: 623 is 3 mm, 608 is 8 mm. For bore codes 04 and up, the last two digits times 5 give the bore: 6004 is 20 mm. Codes 00, 01, 02 and 03 mean 10, 12, 15 and 17 mm (NSK bore number rule). MR bearings carry the bore and outer diameter in the code: MR105 is 5 x 10 mm. A leading F means flanged, a leading S stainless steel, and ZZ or 2RS the closure. The full rules are in our guide to reading bearing codes.
Which bearing has my size?
All sizes in mm, sorted by bore, then outer diameter, then width. Sizes follow the ISO 15 plan for radial bearings; the list is our live catalogue of miniature, flanged and deep groove ball bearings.
Needle roller and linear bearings are listed in their own collections: needle roller bearings and linear bearings.
Why do some sizes have two widths?
Several MR sizes exist in an open version and a slightly wider shielded or sealed version, for example MR52 (2 x 5 x 2 mm) and MR52ZZ (2 x 5 x 2.5 mm). Always measure the width of the bearing you are replacing.
Where can I browse by type?
- Miniature ball bearings and MR series
- Flanged bearings
- Deep groove ball bearings
- Stainless steel bearings and ceramic bearings
- Bearing size chart in mm and 608ZZ vs 608-2RS
Ordering from Precispin: all items are dispatched from Lommel, Belgium within 1–2 working days. Shipping is €4.99 incl. VAT, free from €50 incl. VAT. Delivery after dispatch takes 1–3 working days in Belgium, 5–8 in other EU countries and 7–14 outside the EU. Consumers have a 14-day right of withdrawal. See our shipping policy and refund policy.
Sources
- ISO 15:2017, Rolling bearings: Radial bearings: Boundary dimensions, general plan
- NSK, Rolling bearings for industrial machinery (bearing numbers, bore numbers, seal codes)
Questions and answers
How do I find a bearing by its size?
Measure the bore (d), outer diameter (D) and width (B) in millimetres, then look up d x D x B in the table. Bearings with the same three numbers are interchangeable in size.
How do I measure a bearing?
Use a caliper: measure the inner diameter of the inner ring, the outside of the outer ring, and the width across the rings. Round to the nearest 0.5 mm for miniature bearings and compare with the table.
How do I find the bearing number from the size?
Find your d x D x B in the size table; the designation column gives the matching bearing numbers, for example 8 x 22 x 7 mm is a 608.
What do the numbers in a bearing code mean?
In 6xx miniature bearings the last digit is the bore in mm (623 = 3 mm). From 04 upwards the last two digits times 5 give the bore (6004 = 20 mm); 00, 01, 02 and 03 mean 10, 12, 15 and 17 mm.
Why is a shielded bearing wider than the open one?
Some miniature sizes come in two widths: the shielded or sealed version is slightly wider to make room for the shield, for example MR52 open is 2 mm wide and MR52ZZ is 2.5 mm.
What if my size is not in the table?
The table lists only bearings we stock. Check the bearing size chart for other standard sizes, or contact us with the size and quantity.