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: The first digit tells you the bearing type The opening digit (or digits) identifies the bearing family:

6 — Deep groove ball bearing (the most common type) 7 — Angular contact ball bearing 1 — Self-aligning ball bearing 3 — Tapered roller bearing 5 — Thrust ball bearing UCP / UCF / UCFL — Housed bearing (pillow block or flange unit)

So 6205 is a deep groove ball bearing. 7205 is an angular contact bearing. 30205 is a tapered roller. Step 2: The series digits tell you the cross-section The next one or two digits define the cross-section — how wide and thick the bearing is relative to its bore:

6205 — 6200 series: light cross-section 6305 — 6300 series: medium cross-section (wider and heavier than 6200) 6005 — 6000 series: extra light cross-section

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: The last two digits are the bore size For size codes 04 and above, multiply by 5 to get the bore in millimeters:

6205 → 05 × 5 = 25mm bore 6208 → 08 × 5 = 40mm bore 6212 → 12 × 5 = 60mm bore

The first four codes are exceptions you just have to remember:

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: The suffix tells you the sealing 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. Rubber contact seals on both sides — the most common configuration for general use — are called 2RS1 by SKF, 2RSR by FAG, DDU by NSK, LLU by NTN, and 2RS by Timken. They keep grease in and contaminants out. Metal shields (non-contact) are called 2Z by SKF and FAG, and ZZ by NSK and NTN. They create less friction than rubber seals but aren't fully sealed. Open bearings have no suffix at all — no sealing, requires external lubrication. This is why SKF 6205-2RS1 and FAG 6205-2RSR are the same bearing — different suffix conventions, identical physical design. Step 5: The clearance class The final suffix (if present) describes internal clearance — how much play exists between the rolling elements and raceways:

CN (or no suffix) — Standard clearance, suitable for most applications C3 — Slightly more clearance than standard. Used in applications with temperature variation, press fits, or 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:

6 — Deep groove ball bearing 2 — Light cross-section (6200 series) 05 — 25mm bore (05 × 5) -2RS1 — Rubber contact seals on both sides (SKF designation) 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:

NSK adds "HR" to some tapered roller bearings — HR30205J is just 30205 NTN prefixes tapered rollers with "4T-" — 4T-30205 is just 30205 FAG/Schaeffler uses "-XL" on current-generation bearings — 30205-XL is just 30205 SKF uses "J2/Q" suffix on tapered rollers — 30205 J2/Q is just 30205

In all cases, the base number is what matters for cross-referencing. Don't want to decode manually? Just search the part number at Partmatch — paste any bearing number from any brand and get verified equivalents across all five major manufacturers instantly.