N6 tolerance (hole, IT6)
Hole tolerance class N6 per ISO 286-1:2010: fundamental deviation ES −4 … −27, grade IT6 (6 µm at ≤ 3 mm to 40 µm at 400–500 mm). For an exact size, open the calculator with N6 selected.
- Type
- Hole
- Grade
- IT6
- Tolerance
- 6 … 40 µm
- Fund. deviation
- ES −4 … −27 µm
N6 limits by size range
| Size (mm) | Upper (µm) | Lower (µm) | Ø max (mm) | Ø min (mm) | Upper (mm) | Lower (mm) | Dev. (in) |
|---|---|---|---|---|---|---|---|
| ≤ 3 | −4 | −10 | 2.996 | 2.990 | −0.004 | −0.010 | −0.00016 / −0.00039 |
| 3 – 6 | −5 | −13 | 5.995 | 5.987 | −0.005 | −0.013 | −0.00020 / −0.00051 |
| 6 – 10 | −7 | −16 | 9.993 | 9.984 | −0.007 | −0.016 | −0.00028 / −0.00063 |
| 10 – 14 | −9 | −20 | 13.991 | 13.980 | −0.009 | −0.020 | −0.00035 / −0.00079 |
| 14 – 18 | −9 | −20 | 17.991 | 17.980 | −0.009 | −0.020 | −0.00035 / −0.00079 |
| 18 – 24 | −11 | −24 | 23.989 | 23.976 | −0.011 | −0.024 | −0.00043 / −0.00094 |
| 24 – 30 | −11 | −24 | 29.989 | 29.976 | −0.011 | −0.024 | −0.00043 / −0.00094 |
| 30 – 40 | −12 | −28 | 39.988 | 39.972 | −0.012 | −0.028 | −0.00047 / −0.00110 |
| 40 – 50 | −12 | −28 | 49.988 | 49.972 | −0.012 | −0.028 | −0.00047 / −0.00110 |
| 50 – 65 | −14 | −33 | 64.986 | 64.967 | −0.014 | −0.033 | −0.00055 / −0.00130 |
| 65 – 80 | −14 | −33 | 79.986 | 79.967 | −0.014 | −0.033 | −0.00055 / −0.00130 |
| 80 – 100 | −16 | −38 | 99.984 | 99.962 | −0.016 | −0.038 | −0.00063 / −0.00150 |
| 100 – 120 | −16 | −38 | 119.984 | 119.962 | −0.016 | −0.038 | −0.00063 / −0.00150 |
| 120 – 140 | −20 | −45 | 139.980 | 139.955 | −0.020 | −0.045 | −0.00079 / −0.00177 |
| 140 – 160 | −20 | −45 | 159.980 | 159.955 | −0.020 | −0.045 | −0.00079 / −0.00177 |
| 160 – 180 | −20 | −45 | 179.980 | 179.955 | −0.020 | −0.045 | −0.00079 / −0.00177 |
| 180 – 200 | −22 | −51 | 199.978 | 199.949 | −0.022 | −0.051 | −0.00087 / −0.00201 |
| 200 – 225 | −22 | −51 | 224.978 | 224.949 | −0.022 | −0.051 | −0.00087 / −0.00201 |
| 225 – 250 | −22 | −51 | 249.978 | 249.949 | −0.022 | −0.051 | −0.00087 / −0.00201 |
| 250 – 280 | −25 | −57 | 279.975 | 279.943 | −0.025 | −0.057 | −0.00098 / −0.00224 |
| 280 – 315 | −25 | −57 | 314.975 | 314.943 | −0.025 | −0.057 | −0.00098 / −0.00224 |
| 315 – 355 | −26 | −62 | 354.974 | 354.938 | −0.026 | −0.062 | −0.00102 / −0.00244 |
| 355 – 400 | −26 | −62 | 399.974 | 399.938 | −0.026 | −0.062 | −0.00102 / −0.00244 |
| 400 – 450 | −27 | −67 | 449.973 | 449.933 | −0.027 | −0.067 | −0.00106 / −0.00264 |
| 450 – 500 | −27 | −67 | 499.973 | 499.933 | −0.027 | −0.067 | −0.00106 / −0.00264 |
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 N6
N6 denotes a hole tolerance zone with tight transition deviation in the ISO 286 system. It is used in N6/h5 (Shaft-basis equivalent of H6/n5, for precision parts that must stay fixed on a shared ground shaft without a key.).
At Ø25 mm N6 is −0.011 / −0.024 mm, i.e. 24.976 to 24.989 mm.
How the limits are calculated
N6 uses grade IT6 (a standard tolerance of 13 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); IT6 sets the width below ES. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.