What Is a Bearing Tolerance
Bearing Tolerance Definition:
Bearing tolerance refers to the allowable limits of variation in the dimensions and geometry of a bearing. These tolerances are set by international standards and determine how much the actual size, shape, and fit of a bearing can differ from its specified measurements.
Tolerances are important because they affect how the bearing fits on the shaft and in the housing, as well as how it performs in terms of speed, load capacity, and lifespan. Bearings with tighter (more precise) tolerances are used in high-precision applications, such as machine tools or aerospace equipment, while standard tolerances are suitable for general industrial use.
Tolearance Tables:
Standard tolerances (P0) for radial bearings, excluding tapered roller bearings
| Inner ring | ||||||||||||
| d | tΔdmp1) | tVdsp1) | tVdmp | tΔBs | tVBs | tKia | ||||||
| Diameter series | All | Normal | Modified3) | |||||||||
| > | ≤ | U | L | 7, 8, 92) | 0, 1 | 2, 3, 4 | U | L | L | |||
| mm | μm | μm | μm | μm | μm | μm | ||||||
| – | 2.5 | 0 | –8 | 10 | 8 | 6 | 6 | 0 | –40 | – | 12 | 10 |
| 2.5 | 10 | 0 | –8 | 10 | 8 | 6 | 6 | 0 | –120 | –250 | 15 | 10 |
| 10 | 18 | 0 | –8 | 10 | 8 | 6 | 6 | 0 | –120 | –250 | 20 | 10 |
| 18 | 30 | 0 | –10 | 13 | 10 | 8 | 8 | 0 | –120 | –250 | 20 | 13 |
| 30 | 50 | 0 | –12 | 15 | 12 | 9 | 9 | 0 | –120 | –250 | 20 | 15 |
| 50 | 80 | 0 | –15 | 19 | 19 | 11 | 11 | 0 | –150 | –380 | 25 | 20 |
| 80 | 120 | 0 | –20 | 25 | 25 | 15 | 15 | 0 | –200 | –380 | 25 | 25 |
| 120 | 180 | 0 | –25 | 31 | 31 | 19 | 19 | 0 | –250 | –500 | 30 | 30 |
| 180 | 250 | 0 | –30 | 38 | 38 | 23 | 23 | 0 | –300 | –500 | 30 | 40 |
| 250 | 315 | 0 | –35 | 44 | 44 | 26 | 26 | 0 | –350 | –500 | 35 | 50 |
| 315 | 400 | 0 | –40 | 50 | 50 | 30 | 30 | 0 | –400 | –630 | 40 | 60 |
| 400 | 500 | 0 | –45 | 56 | 56 | 34 | 34 | 0 | –450 | – | 50 | 65 |
| 500 | 630 | 0 | –50 | 63 | 63 | 38 | 38 | 0 | –500 | – | 60 | 70 |
| 630 | 800 | 0 | –75 | – | – | – | – | 0 | –750 | – | 70 | 80 |
| 800 | 1 000 | 0 | –100 | – | – | – | – | 0 | –1 000 | – | 80 | 90 |
| 1 000 | 1 250 | 0 | –125 | – | – | – | – | 0 | –1 250 | – | 100 | 100 |
| 1 250 | 1 600 | 0 | –160 | – | – | – | – | 0 | –1 600 | – | 120 | 120 |
| 1 600 | 2 000 | 0 | –200 | – | – | – | – | 0 | –2 000 | – | 140 | 140 |
| Outer ring | ||||||||||
| D | tΔDmp | tVDsp4) | tVDmp4) | tΔCs | tKea | |||||
| Open bearings | Capped bearings5) | tVCs | ||||||||
| Diameter series | ||||||||||
| > | ≤ | U | L | 7, 8, 92) | 0, 1 | 2, 3, 4 | 2, 3, 4 | |||
| mm | μm | μm | μm | μm | μm | |||||
| 2.5 | 18 | 0 | –8 | 10 | 8 | 6 | 10 | 6 | Identical to tΔBs and tVBs of an inner ring of the same bearing | 15 |
| 18 | 30 | 0 | –9 | 12 | 9 | 7 | 12 | 7 | 15 | |
| 30 | 50 | 0 | –11 | 14 | 11 | 8 | 16 | 8 | 20 | |
| 50 | 80 | 0 | –13 | 16 | 13 | 10 | 20 | 10 | 25 | |
| 80 | 120 | 0 | –15 | 19 | 19 | 11 | 26 | 11 | 35 | |
| 120 | 150 | 0 | –18 | 23 | 23 | 14 | 30 | 14 | 40 | |
| 150 | 180 | 0 | –25 | 31 | 31 | 19 | 38 | 19 | 45 | |
| 180 | 250 | 0 | –30 | 38 | 38 | 23 | – | 23 | 50 | |
| 250 | 315 | 0 | –35 | 44 | 44 | 26 | – | 26 | 60 | |
| 315 | 400 | 0 | –40 | 50 | 50 | 30 | – | 30 | 70 | |
| 400 | 500 | 0 | –45 | 56 | 56 | 34 | – | 34 | 80 | |
| 500 | 630 | 0 | –50 | 63 | 63 | 38 | – | 38 | 100 | |
| 630 | 800 | 0 | –75 | 94 | 94 | 55 | – | 55 | 120 | |
| 800 | 1 000 | 0 | –100 | 125 | 125 | 75 | – | 75 | 140 | |
| 1 000 | 1 250 | 0 | –125 | – | – | – | – | – | 160 | |
| 1 250 | 1 600 | 0 | –160 | – | – | – | – | – | 190 | |
| 1 600 | 2 000 | 0 | –200 | – | – | – | – | – | 220 | |
| 2 000 | 2 500 | 0 | –250 | – | – | – | – | – | 250 | |
P6 class tolerances for radial bearings, excluding tapered roller bearings
| Inner ring | ||||||||||||
| d | tΔdmp1) | tVdsp1) | tVdmp | tΔBs | tVBs | tKia | ||||||
| Diameter series | All | Normal | Modified3) | |||||||||
| > | ≤ | U | L | 7, 8, 92) | 0, 1 | 2, 3, 4 | U | L | L | |||
| mm | μm | μm | μm | μm | μm | μm | ||||||
| – | 2,5 | 0 | –7 | 9 | 7 | 5 | 5 | 0 | –40 | – | 12 | 5 |
| 2,5 | 10 | 0 | –7 | 9 | 7 | 5 | 5 | 0 | –120 | –250 | 15 | 6 |
| 10 | 18 | 0 | –7 | 9 | 7 | 5 | 5 | 0 | –120 | –250 | 20 | 7 |
| 18 | 30 | 0 | –8 | 10 | 8 | 6 | 6 | 0 | –120 | –250 | 20 | 8 |
| 30 | 50 | 0 | –10 | 13 | 10 | 8 | 8 | 0 | –120 | –250 | 20 | 10 |
| 50 | 80 | 0 | –12 | 15 | 15 | 9 | 9 | 0 | –150 | –380 | 25 | 10 |
| 80 | 120 | 0 | –15 | 19 | 19 | 11 | 11 | 0 | –200 | –380 | 25 | 13 |
| 120 | 180 | 0 | –18 | 23 | 23 | 14 | 14 | 0 | –250 | –500 | 30 | 18 |
| 180 | 250 | 0 | –22 | 28 | 28 | 17 | 17 | 0 | –300 | –500 | 30 | 20 |
| 250 | 315 | 0 | –25 | 31 | 31 | 19 | 19 | 0 | –350 | –500 | 35 | 25 |
| 315 | 400 | 0 | –30 | 38 | 38 | 23 | 23 | 0 | –400 | –630 | 40 | 30 |
| 400 | 500 | 0 | –35 | 44 | 44 | 26 | 26 | 0 | –450 | – | 45 | 35 |
| 500 | 630 | 0 | –40 | 50 | 50 | 30 | 30 | 0 | –500 | – | 50 | 40 |
| 630 | 800 | 0 | –50 | – | – | – | – | 0 | –750 | – | 60 | 45 |
| 800 | 1 000 | 0 | –60 | – | – | – | – | 0 | –1 000 | – | 60 | 50 |
| 1 000 | 1 250 | 0 | –75 | – | – | – | – | 0 | –1 250 | – | 70 | 60 |
| 1 250 | 1 600 | 0 | –90 | – | – | – | – | 0 | –1 600 | – | 70 | 70 |
| 1 600 | 2 000 | 0 | –115 | – | – | – | – | 0 | –2 000 | – | 80 | 80 |
| Outer ring | ||||||||||
| D | tΔDmp | tVDsp4) | tVDmp4) | tΔCs | tKea | |||||
| Open bearings | Capped bearings5) | tVCs | ||||||||
| Diameter series | ||||||||||
| > | ≤ | U | L | 7, 8, 92) | 0, 1 | 2, 3, 4 | 0, 1, 2, 3, 4 | |||
| mm | μm | μm | μm | μm | μm | |||||
| 2,5 | 18 | 0 | –7 | 9 | 7 | 5 | 9 | 5 | Identical to | 8 |
| 18 | 30 | 0 | –8 | 10 | 8 | 6 | 10 | 6 | tΔBs and tVBs | 9 |
| 30 | 50 | 0 | –9 | 11 | 9 | 7 | 13 | 7 | of an inner ring | 10 |
| of the same | ||||||||||
| 50 | 80 | 0 | –11 | 14 | 11 | 8 | 16 | 8 | bearing | 13 |
| 80 | 120 | 0 | –13 | 16 | 16 | 10 | 20 | 10 | 18 | |
| 120 | 150 | 0 | –15 | 19 | 19 | 11 | 25 | 11 | 20 | |
| 150 | 180 | 0 | –18 | 23 | 23 | 14 | 30 | 14 | 23 | |
| 180 | 250 | 0 | –20 | 25 | 25 | 15 | – | 15 | 25 | |
| 250 | 315 | 0 | –25 | 31 | 31 | 19 | – | 19 | 30 | |
| 315 | 400 | 0 | –28 | 35 | 35 | 21 | – | 21 | 35 | |
| 400 | 500 | 0 | –33 | 41 | 41 | 25 | – | 25 | 40 | |
| 500 | 630 | 0 | –38 | 48 | 48 | 29 | – | 29 | 50 | |
| 630 | 800 | 0 | –45 | 56 | 56 | 34 | – | 34 | 60 | |
| 800 | 1 000 | 0 | –60 | 75 | 75 | 45 | – | 45 | 75 | |
| 1 000 | 1 250 | 0 | –75 | – | – | – | – | – | 85 | |
| 1 250 | 1 600 | 0 | –90 | – | – | – | – | – | 100 | |
| 1 600 | 2 000 | 0 | –115 | – | – | – | – | – | 100 | |
| 2 000 | 2 500 | 0 | –135 | – | – | – | – | – | ||
The Relationship Between Bearing Tolerance and Limit Dimensions:
As mentioned above, bearing dimensional tolerance refers to the permissible variation in the actual size of a bearing from its nominal (design) size. Limit dimensions, on the other hand, are the maximum and minimum allowable dimensions that a bearing can have according to specified standards.
The relationship between them is that the tolerance defines the range within which the actual bearing size must fall, while the limit dimensions specify the exact upper and lower boundaries of this range. In other words, the tolerance is the difference between the maximum and minimum limit dimensions. Adhering to these tolerances and limit dimensions ensures that bearings fit and function properly in their applications.
Why Bearing Dimensions Matter?
Bearings are high-precision components that require strict adherence to dimensional specifications. If the dimensions deviate beyond acceptable limits, several issues can arise:
Excessive Clearance: This can reduce operational accuracy and cause vibration.
Overly Tight Fit: This increases friction, which may lead to overheating or even bearing seizure.
Accelerated Wear: Dimensional inaccuracies can shorten the bearing’s service life.
Installation Challenges: Improper dimensions make assembly more difficult, impacting both efficiency and cost.
Therefore, understanding bearing dimensional tolerances and limit dimensions is crucial for both buyers and engineers.
