6300 Series Bearings
The medium series: the largest outside diameter and width of the three at any given bore, and therefore the highest load capacity and the stiffest shaft support — in exchange for the biggest housing.
Medium serieswhere it sits and what it trades away
The 6300 series is the medium diameter series — the digit 3 in the second position. For a given bore it is the largest of the three series on this site: thicker rings, a wider section, and more room inside for rolling elements, all of which show up as load capacity and as shaft stiffness. The price is the housing bore. On a 20 mm shaft a 6304 is 52 mm across, against 47 mm for the light 6204 and 42 mm for the extra-light 6004.
The step from light to medium is not a small one in housing terms — at the same bore the outside diameter grows by more than the extra-light to light step did — but the capacity gain is the largest of the two steps as well. That makes the medium series the usual answer when a light-series bearing has been failing under load on a shaft whose diameter is fixed: the 6305 takes the same 25 mm shaft as the 6205 and the housing is the only thing that has to change.
The series runs from 6300 (10 mm bore, 35 mm outside diameter, 11 mm wide) to 6320 (100 mm bore, 215 mm outside diameter, 47 mm wide) in the 21 designations tabulated here. Note how quickly the outside diameter grows at the top end — 6320 is more than twice the bore across — which is the practical limit on how far the "just fit a bigger series" answer can be pushed before the housing becomes the problem.
Every designation in the table below links to its own page with the ISO 15 dimensions, the bore-code arithmetic, the ISO 5753-1 clearance ranges for its bore, and the same-bore comparison against the 60 and 62 series.
All 21 designationsISO 15 boundary dimensions, mm
| Designation | Bore code | d | D | B | r s min | Section (D − d)/2 |
|---|---|---|---|---|---|---|
| 6300 | 00 | 10 | 35 | 11 | 0.6 | 12.5 |
| 6301 | 01 | 12 | 37 | 12 | 1 | 12.5 |
| 6302 | 02 | 15 | 42 | 13 | 1 | 13.5 |
| 6303 | 03 | 17 | 47 | 14 | 1 | 15 |
| 6304 | 04 | 20 | 52 | 15 | 1.1 | 16 |
| 6305 | 05 | 25 | 62 | 17 | 1.1 | 18.5 |
| 6306 | 06 | 30 | 72 | 19 | 1.1 | 21 |
| 6307 | 07 | 35 | 80 | 21 | 1.5 | 22.5 |
| 6308 | 08 | 40 | 90 | 23 | 1.5 | 25 |
| 6309 | 09 | 45 | 100 | 25 | 1.5 | 27.5 |
| 6310 | 10 | 50 | 110 | 27 | 2 | 30 |
| 6311 | 11 | 55 | 120 | 29 | 2 | 32.5 |
| 6312 | 12 | 60 | 130 | 31 | 2.1 | 35 |
| 6313 | 13 | 65 | 140 | 33 | 2.1 | 37.5 |
| 6314 | 14 | 70 | 150 | 35 | 2.1 | 40 |
| 6315 | 15 | 75 | 160 | 37 | 2.1 | 42.5 |
| 6316 | 16 | 80 | 170 | 39 | 2.1 | 45 |
| 6317 | 17 | 85 | 180 | 41 | 3 | 47.5 |
| 6318 | 18 | 90 | 190 | 43 | 3 | 50 |
| 6319 | 19 | 95 | 200 | 45 | 3 | 52.5 |
| 6320 | 20 | 100 | 215 | 47 | 3 | 57.5 |
d = bore, D = outside diameter, B = width, r s min = minimum single chamfer dimension. All four are ISO 15 standard values and are the same for every manufacturer. The last column is derived: radial section = (D − d) / 2, the wall thickness you are working with when you size the housing. No load rating and no limiting speed appears here — see the bearings index for why.
The three series at one boresame shaft, different housing
| Series | Type | 10 mm bore | 12 mm bore | 15 mm bore | 17 mm bore | 20 mm bore |
|---|---|---|---|---|---|---|
| 6000 Series | Extra-light | 26 × 8 | 28 × 8 | 32 × 9 | 35 × 10 | 42 × 12 |
| 6200 Series | Light | 30 × 9 | 32 × 10 | 35 × 11 | 40 × 12 | 47 × 14 |
| 6300 Series | Medium | 35 × 11 | 37 × 12 | 42 × 13 | 47 × 14 | 52 × 15 |
Outside diameter × width in millimetres, for the five smallest bores in this batch. The full chart across all 21 bores and all three series is on the bearings index. Reading a row is what a machine designer does when the shaft is already fixed: the bore does not change, the housing bore does.
Frequently asked questionsreading a bearing designation
When should I step up from the 6200 to the 6300 series?
When the shaft diameter is fixed by the machine and the light-series bearing is the part that keeps failing — or when the housing simply has room. Same bore, larger outside diameter and width, more capacity, no change to the shaft. The housing bore is the price.
Is the 6300 series interchangeable with the 6200 series?
No. Only the bore matches. A 6305 and a 6205 both take a 25 mm shaft, but the 6305 is 62 mm across against 52 mm, and 17 mm wide against 15 mm. Fitting one where the other was designed means a different housing and a different axial location.
Does the medium series run hotter or slower than the light series?
Not as a rule of the standard — friction and speed capability depend on the internal design, the cage, the lubrication and the seals, none of which ISO 15 constrains. A bigger bearing has a larger rolling-element circle and therefore higher surface speeds at the same revolutions, which is one of several reasons the limiting speed in a catalogue falls as bearings get larger. That is catalogue data, and it is not published here.