How to Read a Bearing Part Number (With Examples)
Every bearing part number tells you exactly what the bearing is — its type, size, sealing, and clearance — if you know how to read it. This guide breaks down the most common formats used by SKF, FAG, NSK, NTN, and Timken.
The Basic Structure
Most bearing part numbers follow this pattern:
Type prefix → Series → Size code → Seal/shield suffix → Clearance suffix
Take SKF 6205-2RS1 C3 as an example. By the end of this guide you'll know exactly what every part of that number means.
Step 1: Bearing Type
The opening digit (or digits) identifies the bearing family.
| Digit/Prefix | Bearing Type | Example |
|---|---|---|
| 6 | Deep groove ball bearing (most common) | 6205 |
| 7 | Angular contact ball bearing | 7205 |
| 1 | Self-aligning ball bearing | 1205 |
| 3 | Tapered roller bearing | 30205 |
| 5 | Thrust ball bearing | 51105 |
| UCP / UCF / UCFL | Housed bearing (pillow block or flange unit) | UCP205 |
So 6205 is a deep groove ball bearing. 7205 is an angular contact bearing. 30205 is a tapered roller.
Step 2: Series (Cross-Section)
The next one or two digits define the cross-section — how wide and thick the bearing is relative to its bore.
| Series | Cross-Section | Description |
|---|---|---|
| 6200 (e.g., 6205) | Light | Standard general-purpose |
| 6300 (e.g., 6305) | Medium | Wider and heavier than 6200, higher load rating |
| 6000 (e.g., 6005) | Extra light | Compact applications |
For the same bore size, a 6305 is physically bigger and has a higher load rating than a 6205. Same bore, different capacity.
Step 3: Bore Size
For size codes 04 and above, multiply by 5 to get the bore in millimeters.
| Size Code | Bore | Calculation |
|---|---|---|
| 04 | 20mm | 04 × 5 |
| 05 | 25mm | 05 × 5 |
| 06 | 30mm | 06 × 5 |
| 08 | 40mm | 08 × 5 |
| 12 | 60mm | 12 × 5 |
The first four codes are exceptions you just have to remember:
| Size Code | Bore |
|---|---|
| 00 | 10mm |
| 01 | 12mm |
| 02 | 15mm |
| 03 | 17mm |
So 6205 = deep groove, light series, 25mm bore. Every brand that makes a 6205 makes it to these exact same ISO dimensions.
Step 4: Sealing Suffix
After the base number, suffixes describe how the bearing is sealed. The confusing part is that every brand uses different letters for the same thing.
Double rubber contact seal (most common)
| Manufacturer | Suffix | Example |
|---|---|---|
| SKF | 2RS1 | 6205-2RS1 |
| FAG | 2RSR | 6205-2RSR |
| NSK | DDU | 6205DDU |
| NTN | LLU | 6205LLU |
| Timken | 2RS | 6205-2RS |
These keep grease in and contaminants out.
Metal shields (non-contact)
| Manufacturer | Suffix |
|---|---|
| SKF, FAG | 2Z |
| NSK, NTN | ZZ |
Metal shields create less friction than rubber seals but aren't fully sealed.
Open
No suffix at all. No sealing — requires external lubrication.
SKF 6205-2RS1 and FAG 6205-2RSR are the same bearing — different suffix conventions, identical physical design. For more on seal types and when to use each, see our guide on what does 2RS mean on a bearing.
Step 5: Clearance Class
The final suffix (if present) describes internal clearance — how much play exists between the rolling elements and raceways.
| Suffix | Clearance | Typical Use |
|---|---|---|
| CN (or no suffix) | Standard | Most applications |
| C3 | Slightly more than standard | Temperature variation, press fits, higher speeds |
| C4 | Even more clearance | Heavy-duty, high-temperature applications |
So 6205-2RS1 C3 is a rubber-sealed deep groove ball bearing, 25mm bore, with C3 clearance.
The C3 designation is important — don't substitute a CN bearing where a C3 is specified.
Putting It All Together
Let's decode SKF 6205-2RS1 C3 completely:
| Component | Code | Meaning |
|---|---|---|
| Type | 6 | Deep groove ball bearing |
| Series | 2 | Light cross-section (6200 series) |
| Bore | 05 | 25mm (05 × 5) |
| Seal | -2RS1 | Rubber contact seals on both sides (SKF designation) |
| Clearance | C3 | Greater than normal internal clearance |
Dimensions: 25 × 52 × 15mm Load rating: 14.8 kN dynamic
And FAG 6205-2RSR, NSK 6205DDU, NTN 6205LLU, and Timken 6205-2RS are all the same bearing with different names.
Brand-Specific Quirks to Know
A few naming conventions that trip people up:
| Manufacturer | Quirk | Example | Cross-Reference As |
|---|---|---|---|
| NSK | "HR" prefix on some tapered rollers | HR30205J | 30205 |
| NTN | "4T-" prefix on tapered rollers | 4T-30205 | 30205 |
| FAG/Schaeffler | "-XL" on current-generation bearings | 30205-XL | 30205 |
| SKF | "J2/Q" suffix on tapered rollers | 30205 J2/Q | 30205 |
In all cases, the base number is what matters for cross-referencing.
Don't Want to Decode Manually?
Just search the part number on Partmatch — paste any bearing number from any brand and get verified equivalents across all five major manufacturers instantly.
For more on bearing nomenclature and selection:
- What does 2RS mean on a bearing?
- SKF vs FAG bearings — which should you choose?
- Agricultural bearing cross-reference
Partmatch provides verified bearing cross-references across SKF, FAG, NSK, NTN, Timken, and 30+ other manufacturers. Search any part number to find equivalents and pricing.