f8 tolerance (shaft, IT8)
Shaft tolerance class f8 per ISO 286-1:2010: fundamental deviation es −6 … −68, grade IT8 (14 µm at ≤ 3 mm to 97 µm at 400–500 mm). For an exact size, open the calculator with f8 selected.
- Type
- Shaft
- Grade
- IT8
- Tolerance
- 14 … 97 µm
- Fund. deviation
- es −6 … −68 µm
f8 limits by size range
| Size (mm) | Upper (µm) | Lower (µm) | Ø max (mm) | Ø min (mm) | Upper (mm) | Lower (mm) | Dev. (in) |
|---|---|---|---|---|---|---|---|
| ≤ 3 | −6 | −20 | 2.994 | 2.980 | −0.006 | −0.020 | −0.00024 / −0.00079 |
| 3 – 6 | −10 | −28 | 5.990 | 5.972 | −0.010 | −0.028 | −0.00039 / −0.00110 |
| 6 – 10 | −13 | −35 | 9.987 | 9.965 | −0.013 | −0.035 | −0.00051 / −0.00138 |
| 10 – 14 | −16 | −43 | 13.984 | 13.957 | −0.016 | −0.043 | −0.00063 / −0.00169 |
| 14 – 18 | −16 | −43 | 17.984 | 17.957 | −0.016 | −0.043 | −0.00063 / −0.00169 |
| 18 – 24 | −20 | −53 | 23.980 | 23.947 | −0.020 | −0.053 | −0.00079 / −0.00209 |
| 24 – 30 | −20 | −53 | 29.980 | 29.947 | −0.020 | −0.053 | −0.00079 / −0.00209 |
| 30 – 40 | −25 | −64 | 39.975 | 39.936 | −0.025 | −0.064 | −0.00098 / −0.00252 |
| 40 – 50 | −25 | −64 | 49.975 | 49.936 | −0.025 | −0.064 | −0.00098 / −0.00252 |
| 50 – 65 | −30 | −76 | 64.970 | 64.924 | −0.030 | −0.076 | −0.00118 / −0.00299 |
| 65 – 80 | −30 | −76 | 79.970 | 79.924 | −0.030 | −0.076 | −0.00118 / −0.00299 |
| 80 – 100 | −36 | −90 | 99.964 | 99.910 | −0.036 | −0.090 | −0.00142 / −0.00354 |
| 100 – 120 | −36 | −90 | 119.964 | 119.910 | −0.036 | −0.090 | −0.00142 / −0.00354 |
| 120 – 140 | −43 | −106 | 139.957 | 139.894 | −0.043 | −0.106 | −0.00169 / −0.00417 |
| 140 – 160 | −43 | −106 | 159.957 | 159.894 | −0.043 | −0.106 | −0.00169 / −0.00417 |
| 160 – 180 | −43 | −106 | 179.957 | 179.894 | −0.043 | −0.106 | −0.00169 / −0.00417 |
| 180 – 200 | −50 | −122 | 199.950 | 199.878 | −0.050 | −0.122 | −0.00197 / −0.00480 |
| 200 – 225 | −50 | −122 | 224.950 | 224.878 | −0.050 | −0.122 | −0.00197 / −0.00480 |
| 225 – 250 | −50 | −122 | 249.950 | 249.878 | −0.050 | −0.122 | −0.00197 / −0.00480 |
| 250 – 280 | −56 | −137 | 279.944 | 279.863 | −0.056 | −0.137 | −0.00220 / −0.00539 |
| 280 – 315 | −56 | −137 | 314.944 | 314.863 | −0.056 | −0.137 | −0.00220 / −0.00539 |
| 315 – 355 | −62 | −151 | 354.938 | 354.849 | −0.062 | −0.151 | −0.00244 / −0.00594 |
| 355 – 400 | −62 | −151 | 399.938 | 399.849 | −0.062 | −0.151 | −0.00244 / −0.00594 |
| 400 – 450 | −68 | −165 | 449.932 | 449.835 | −0.068 | −0.165 | −0.00268 / −0.00650 |
| 450 – 500 | −68 | −165 | 499.932 | 499.835 | −0.068 | −0.165 | −0.00268 / −0.00650 |
Deviations at the upper end of each range (Ø columns use that size); use the calculator for the exact size. — : not defined by ISO 286 for that size. Upper/Lower (mm) and inch columns are shown on wider screens.
About f8
f8 denotes a shaft tolerance zone with close running deviation in the ISO 286 system. It is used in H9/f8 (Easy-running clearance for shafts in plain bearings where moderate speed and normal lubrication are expected but full IT7 precision isn't needed: fans, light gearboxes, farm-machinery drivetrains.).
At Ø25 mm f8 is −0.020 / −0.053 mm, i.e. 24.947 to 24.980 mm.
How the limits are calculated
f8 uses grade IT8 (a standard tolerance of 33 µm at 18–30 mm). Fundamental deviation: es is tabulated directly by ISO 286-1 Table 2; ei = es − IT8. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.