What a bearing number means
Read a metric bearing number from the left. The first digit is the type: 6 is single-row deep groove, 2 is spherical roller, 3 is taper roller, 7 is angular contact. The second digit is the dimension series, where 0 is light, 2 is medium and 3 is heavy for the same bore.
The last two digits are the bore code. From 04 upward, multiply by 5 to get the bore in millimetres. Below that they are fixed: 00 is 10mm, 01 is 12mm, 02 is 15mm and 03 is 17mm.
So a 6205 and a 6305 share a 25mm bore, but the 6305 is physically bigger and carries more load.
| Suffix | Meaning |
|---|---|
| Open | No seal or shield |
| Z / ZZ | One or two metal shields, non-contact |
| RS / 2RS | One or two rubber contact seals |
| C2 | Reduced internal clearance |
| C3 | Increased internal clearance, for heat or interference fits |
| C4 | Greater than C3 |
| N / NR | Snap ring groove, NR includes the ring |
Ball bearing size chart
All three series below share the same bore for a given last-two-digit code. Pick the series by load: 6200 covers most general machinery, 6300 is the heavier option when the same shaft has to carry more, and 6000 is the slim choice when radial space is tight.
| Bore (mm) | 6000 series | 6200 series | 6300 series |
|---|---|---|---|
| 10 | 6000: 10x26x8 | 6200: 10x30x9 | 6300: 10x35x11 |
| 12 | 6001: 12x28x8 | 6201: 12x32x10 | 6301: 12x37x12 |
| 15 | 6002: 15x32x9 | 6202: 15x35x11 | 6302: 15x42x13 |
| 17 | 6003: 17x35x10 | 6203: 17x40x12 | 6303: 17x47x14 |
| 20 | 6004: 20x42x12 | 6204: 20x47x14 | 6304: 20x52x15 |
| 25 | 6005: 25x47x12 | 6205: 25x52x15 | 6305: 25x62x17 |
| 30 | 6006: 30x55x13 | 6206: 30x62x16 | 6306: 30x72x19 |
| 35 | 6007: 35x62x14 | 6207: 35x72x17 | 6307: 35x80x21 |
| 40 | 6008: 40x68x15 | 6208: 40x80x18 | 6308: 40x90x23 |
Bearing cross reference
The base number is standardised, so a 6203-2RS from any manufacturer has the same 17 x 40 x 12 envelope and will physically fit. What differs is the suffix system: the same bearing is 6203-2RS1 at one maker, 6203-2RSR at another and 6203-DDU at a third.
Cross-reference on the base number and the seal type, then check the clearance code separately. Substituting a C3 bearing where the drawing calls for standard clearance, or the reverse, changes how the bearing behaves once it warms up.
