F8 tolerance (hole, IT8)
Hole tolerance class F8 per ISO 286-1:2010: fundamental deviation EI +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
- Hole
- Grade
- IT8
- Tolerance
- 14 … 97 µm
- Fund. deviation
- EI +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 | +20 | +6 | 3.020 | 3.006 | +0.020 | +0.006 | +0.00079 / +0.00024 |
| 3 – 6 | +28 | +10 | 6.028 | 6.010 | +0.028 | +0.010 | +0.00110 / +0.00039 |
| 6 – 10 | +35 | +13 | 10.035 | 10.013 | +0.035 | +0.013 | +0.00138 / +0.00051 |
| 10 – 14 | +43 | +16 | 14.043 | 14.016 | +0.043 | +0.016 | +0.00169 / +0.00063 |
| 14 – 18 | +43 | +16 | 18.043 | 18.016 | +0.043 | +0.016 | +0.00169 / +0.00063 |
| 18 – 24 | +53 | +20 | 24.053 | 24.020 | +0.053 | +0.020 | +0.00209 / +0.00079 |
| 24 – 30 | +53 | +20 | 30.053 | 30.020 | +0.053 | +0.020 | +0.00209 / +0.00079 |
| 30 – 40 | +64 | +25 | 40.064 | 40.025 | +0.064 | +0.025 | +0.00252 / +0.00098 |
| 40 – 50 | +64 | +25 | 50.064 | 50.025 | +0.064 | +0.025 | +0.00252 / +0.00098 |
| 50 – 65 | +76 | +30 | 65.076 | 65.030 | +0.076 | +0.030 | +0.00299 / +0.00118 |
| 65 – 80 | +76 | +30 | 80.076 | 80.030 | +0.076 | +0.030 | +0.00299 / +0.00118 |
| 80 – 100 | +90 | +36 | 100.090 | 100.036 | +0.090 | +0.036 | +0.00354 / +0.00142 |
| 100 – 120 | +90 | +36 | 120.090 | 120.036 | +0.090 | +0.036 | +0.00354 / +0.00142 |
| 120 – 140 | +106 | +43 | 140.106 | 140.043 | +0.106 | +0.043 | +0.00417 / +0.00169 |
| 140 – 160 | +106 | +43 | 160.106 | 160.043 | +0.106 | +0.043 | +0.00417 / +0.00169 |
| 160 – 180 | +106 | +43 | 180.106 | 180.043 | +0.106 | +0.043 | +0.00417 / +0.00169 |
| 180 – 200 | +122 | +50 | 200.122 | 200.050 | +0.122 | +0.050 | +0.00480 / +0.00197 |
| 200 – 225 | +122 | +50 | 225.122 | 225.050 | +0.122 | +0.050 | +0.00480 / +0.00197 |
| 225 – 250 | +122 | +50 | 250.122 | 250.050 | +0.122 | +0.050 | +0.00480 / +0.00197 |
| 250 – 280 | +137 | +56 | 280.137 | 280.056 | +0.137 | +0.056 | +0.00539 / +0.00220 |
| 280 – 315 | +137 | +56 | 315.137 | 315.056 | +0.137 | +0.056 | +0.00539 / +0.00220 |
| 315 – 355 | +151 | +62 | 355.151 | 355.062 | +0.151 | +0.062 | +0.00594 / +0.00244 |
| 355 – 400 | +151 | +62 | 400.151 | 400.062 | +0.151 | +0.062 | +0.00594 / +0.00244 |
| 400 – 450 | +165 | +68 | 450.165 | 450.068 | +0.165 | +0.068 | +0.00650 / +0.00268 |
| 450 – 500 | +165 | +68 | 500.165 | 500.068 | +0.165 | +0.068 | +0.00650 / +0.00268 |
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 hole tolerance zone with close running deviation in the ISO 286 system. It is used in F8/h7 (Shaft-basis equivalent of H8/f7 for bearings on a plain shaft.).
At Ø25 mm F8 is +0.053 / +0.020 mm, i.e. 25.020 to 25.053 mm.
How the limits are calculated
F8 uses grade IT8 (a standard tolerance of 33 µm at 18–30 mm). Fundamental deviation: EI = −es of the same shaft letter; IT8 sets the width above EI. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.