How to read a bearing designation
A designation has two parts: the basic number says what the bearing is and how big, the suffixes say how it is built. The basic number is shared across manufacturers; the suffixes each writes their own way. Both are below, with examples from our catalogue.
Short answer
Take 6205-C-2Z-C3. The first part, 6205, is the basic number: bearing type, dimension series and size. Everything after the first hyphen is the design — here Generation C, shields on both sides (2Z) and clearance greater than normal (C3).
The basic number is the same at every manufacturer: 6205 is 6205 at SKF, NSK, NTN and KOYO. Only the suffixes differ — and they are what makes one and the same item look like four different products.
The basic number tells you whether it fits. The suffixes tell you whether it will last in your conditions.
The bore is in the last two digits
In four-digit numbers of series 60xx, 62xx and 63xx, the last two digits multiplied by five give the bore in millimetres. 6205 is a 25 mm bore, 6004 is 20 mm, 6310 is 50 mm.
We checked this by querying our own catalogue: of 2 489 items in those series for which we hold a measured bore, the rule holds for all 2 489. It applies from 20 mm upwards — for smaller sizes (suffixes 00 to 03) the values come from a table, not from multiplication.
The first digit is the type (6 — deep groove ball, 7 — angular contact, 2 and 3 — spherical roller, 1 — self-aligning), the second is the dimension series, that is how heavy the bearing is at the same bore. Hence 6205, 6305 and 6405 share a 25 mm bore but differ in outside diameter and width.
6205 → 05 × 5 = 25 mm bore. Verified on 2 489 items of our catalogue.
The suffixes that change the purchase
Not every suffix matters when ordering — some describe manufacturing detail. The ones below decide whether the bearing survives in your machine. In brackets: how many items in our catalogue carry that suffix.
| Suffix | Meaning | When it matters |
|---|---|---|
| 2Z (1,070) | shields on both sides | high speed, clean environment — a shield does not touch the ring, so it adds no friction |
| Z | shield on one side | where the other side is closed by the design |
| 2RSR, 2HRS | contact seals on both sides | dust, moisture, wash-down — at slightly higher friction |
| C3 (3,876) | radial clearance greater than normal | heat or a tight fit — thermal expansion eats the clearance |
| C4 (1,269) | clearance greater than C3 | high operating temperature, large difference in shaft and housing warming |
| CN | normal clearance | standard design; no clearance suffix means the same |
| K (1,098) | tapered bore, taper 1:12 | mounting on an adapter sleeve or a tapered shaft, with clearance set on assembly |
| TVH, TVP | plastic cage | lighter rotating set, less internal friction |
| M, MA (1,296) | solid brass cage | high temperature and shock loads, where plastic is not enough |
| XL (8,405) | the manufacturer's X-life design | higher service life in the same envelope |
The meanings come from the manufacturer's descriptions in our own item data, not from generic suffix tables.
The same bearing at other manufacturers
The basic number is shared, so 6205 is recognisable anywhere. Trouble starts with sealing and clearance: the same design is 2RS1 at SKF, DDU at NSK, LLU at NTN and DD at KOYO. Someone searching for “6205 2RS” finds nothing under that spelling here — what we hold is 6205-C-2HRS.
Below are the two most common designs in four systems. The data comes from our cross-reference table, which holds 13,851 SKF designations, 5,837 NSK, 4,739 NTN and 2,992 KOYO.
| Design | ours (FAG) | SKF | NSK | NTN | KOYO |
|---|---|---|---|---|---|
| shields both sides | 6205-C-2Z | 6205-2Z | 6205ZZ | 6205ZZ | 6205ZZ |
| seals both sides | 6205-C-2HRS | 6205-2RS1, 6205-2RSH | 6205DDU | 6205LLU | 6205DD |
| seals + C3 clearance | 6205-C-2HRS-C3 | 6205-2RS1/C3 | 6205DDUC3E | 6205LLUC3 | 6205DDC3 |
ZZ, DDU, LLU and 2RS1 are the same thing as our 2Z and 2HRS — only the spelling differs.
What the designation does not tell you
A designation says nothing about load ratings, accuracy class or factory grease — and those decide when the bearing runs near its limits. Two bearings with the same designation from two manufacturers can differ in dynamic load rating and in limiting speed.
That is why a replacement chosen from the designation alone is a dimensional and design equivalent, not the same product. In a critical application, check the load rating, limiting speed and tolerance class of the specific design on its datasheet.
Source
Suffix meanings — manufacturer descriptions in our catalogue data. The bore rule — verified on 2,489 items of series 60xx–63xx in that catalogue. Other manufacturers' notations — our cross-reference table (SKF 13,851, NSK 5,837, NTN 4,739, KOYO 2,992 designations).