How to read a deep groove ball bearing model number (with 4 exceptions from our own catalogue)
2026-09-16
Using our own parameter table to explain the three parts of a model number — series prefix, bore code and seal suffix — and why the same bore does not mean interchangeable.
The question we hear most often: "6205 and 6305 both have a 25 mm bore — can I swap them?" No. To read a model number, start with its three parts.
A model number = series prefix + bore code + seal suffix
Take `6205-2RS`:
| Part | Value | Meaning |
|---|---|---|
| Series prefix | `62` | Together with the bore, determines the outer diameter and width (look it up in the table) |
| Bore code | `05` | Determines the bore (shaft diameter) |
| Seal suffix | `-2RS` | Determines the sealing arrangement |
The key point: two models with the same bore usually have different outer diameters and widths — so they will not fit the same housing. A matching bore does not mean a drop-in replacement.
Reading the bore code
| Code | Bore |
|---|---|
| `00` | 10 mm |
| `01` | 12 mm |
| `02` | 15 mm |
| `03` | 17 mm |
| `04`–`96` (the usual range) | code × 5 mm (`05` → 25 mm, `08` → 40 mm) |
Three-digit base models in our catalogue (such as `608`, `685`, `689`) work differently: the last digit is the bore directly (8 mm, 5 mm, 9 mm) — do not multiply by five. (Note these are not all from one series — `608`, for example, belongs to the 60 series. What is described here is only how a three-digit designation reads.)
We verified this rule against all 100 base models in our own catalogue, and every one matched.
Four exceptions in our catalogue
A few models use a slash form, and the meaning is not the same in each case. Where a model looks unusual, take the dimensions from that model's own page:
| Model | Bore | Note |
|---|---|---|
| `60/22` | 22 mm | Only a series prefix before the slash, so the number after the slash is the actual bore |
| `62/28` | 28 mm | Same |
| `62/32` | 32 mm | Same |
| `6203/42` | 17 mm | Different — the part before the slash is already a complete model (`03` → 17 mm); in our catalogue this model has a 42 mm outer diameter (a standard 6203 has 40 mm). |
Note: the number after the slash does not mean the same thing across these four models (for the first three it refers to the bore, for the last it does not). We therefore do not generalise a "slash rule" — where a slash appears, take the dimensions from that model's own page.
If you come across any non-standard designation, send it to us and we will confirm — please do not infer from the characters alone.
Seal suffixes: the trade-off between speed and protection
The seal variants in our catalogue:
| Suffix | Construction |
|---|---|
| (none / open) | Open both sides |
| `Z` / `ZZ` | One / both sides metal shields |
| `RZ` / `2RZ` | One / both sides rubber seals (light-contact type) |
| `RS` / `2RS` | One / both sides contact rubber seals |
On the contact form for `RZ`/`2RZ`: our factory parameter table records only the seal code and material (NBR), not a per-model contact type. The wording above follows our own material; where it matters, take the factory's confirmation as authoritative — we do not adjudicate it here.
Which suffix fits depends on dust, moisture and maintenance conditions — and it also affects the grease-lubricated limiting speed. We cover that trade-off in a separate article.
In one line
The same bore does not mean interchangeable. Read the series prefix, the bore code and the seal suffix together — the outer diameter and width come from the series prefix combined with the bore.
⚠️ A model number alone is not enough to specify a bearing: for the actual outer diameter, width, load ratings and limiting speeds, use the figures on that model's own page, or ask us to confirm.
To screen models by your shaft diameter, available envelope, speed and environment, use the bearing selector — or send us your application and our engineers will confirm the final selection.