K8 tolerance (hole, IT8)
Hole tolerance class K8 per ISO 286-1:2010: fundamental deviation ES 0 … +29, grade IT8 (14 µm at ≤ 3 mm to 97 µm at 400–500 mm). For an exact size, open the calculator with K8 selected.
- Type
- Hole
- Grade
- IT8
- Tolerance
- 14 … 97 µm
- Fund. deviation
- ES 0 … +29 µm
K8 limits by size range
| Size (mm) | Upper (µm) | Lower (µm) | Ø max (mm) | Ø min (mm) | Upper (mm) | Lower (mm) | Dev. (in) |
|---|---|---|---|---|---|---|---|
| ≤ 3 | 0 | −14 | 3.000 | 2.986 | 0 | −0.014 | 0 / −0.00055 |
| 3 – 6 | +5 | −13 | 6.005 | 5.987 | +0.005 | −0.013 | +0.00020 / −0.00051 |
| 6 – 10 | +6 | −16 | 10.006 | 9.984 | +0.006 | −0.016 | +0.00024 / −0.00063 |
| 10 – 14 | +8 | −19 | 14.008 | 13.981 | +0.008 | −0.019 | +0.00031 / −0.00075 |
| 14 – 18 | +8 | −19 | 18.008 | 17.981 | +0.008 | −0.019 | +0.00031 / −0.00075 |
| 18 – 24 | +10 | −23 | 24.010 | 23.977 | +0.010 | −0.023 | +0.00039 / −0.00091 |
| 24 – 30 | +10 | −23 | 30.010 | 29.977 | +0.010 | −0.023 | +0.00039 / −0.00091 |
| 30 – 40 | +12 | −27 | 40.012 | 39.973 | +0.012 | −0.027 | +0.00047 / −0.00106 |
| 40 – 50 | +12 | −27 | 50.012 | 49.973 | +0.012 | −0.027 | +0.00047 / −0.00106 |
| 50 – 65 | +14 | −32 | 65.014 | 64.968 | +0.014 | −0.032 | +0.00055 / −0.00126 |
| 65 – 80 | +14 | −32 | 80.014 | 79.968 | +0.014 | −0.032 | +0.00055 / −0.00126 |
| 80 – 100 | +16 | −38 | 100.016 | 99.962 | +0.016 | −0.038 | +0.00063 / −0.00150 |
| 100 – 120 | +16 | −38 | 120.016 | 119.962 | +0.016 | −0.038 | +0.00063 / −0.00150 |
| 120 – 140 | +20 | −43 | 140.020 | 139.957 | +0.020 | −0.043 | +0.00079 / −0.00169 |
| 140 – 160 | +20 | −43 | 160.020 | 159.957 | +0.020 | −0.043 | +0.00079 / −0.00169 |
| 160 – 180 | +20 | −43 | 180.020 | 179.957 | +0.020 | −0.043 | +0.00079 / −0.00169 |
| 180 – 200 | +22 | −50 | 200.022 | 199.950 | +0.022 | −0.050 | +0.00087 / −0.00197 |
| 200 – 225 | +22 | −50 | 225.022 | 224.950 | +0.022 | −0.050 | +0.00087 / −0.00197 |
| 225 – 250 | +22 | −50 | 250.022 | 249.950 | +0.022 | −0.050 | +0.00087 / −0.00197 |
| 250 – 280 | +25 | −56 | 280.025 | 279.944 | +0.025 | −0.056 | +0.00098 / −0.00220 |
| 280 – 315 | +25 | −56 | 315.025 | 314.944 | +0.025 | −0.056 | +0.00098 / −0.00220 |
| 315 – 355 | +28 | −61 | 355.028 | 354.939 | +0.028 | −0.061 | +0.00110 / −0.00240 |
| 355 – 400 | +28 | −61 | 400.028 | 399.939 | +0.028 | −0.061 | +0.00110 / −0.00240 |
| 400 – 450 | +29 | −68 | 450.029 | 449.932 | +0.029 | −0.068 | +0.00114 / −0.00268 |
| 450 – 500 | +29 | −68 | 500.029 | 499.932 | +0.029 | −0.068 | +0.00114 / −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 K8
K8 denotes a hole tolerance zone with transition deviation in the ISO 286 system.
At Ø25 mm K8 is +0.010 / −0.023 mm, i.e. 24.977 to 25.010 mm.
How the limits are calculated
K8 uses grade IT8 (a standard tolerance of 33 µm at 18–30 mm). Fundamental deviation: ES = −ei + Δ (Δ = ITn − IT(n−1), applied up to IT8 for K/M/N and IT7 otherwise); IT8 sets the width below ES. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.