N7 tolerance (hole, IT7)
Hole tolerance class N7 per ISO 286-1:2010: fundamental deviation ES −4 … −17, grade IT7 (10 µm at ≤ 3 mm to 63 µm at 400–500 mm). For an exact size, open the calculator with N7 selected.
- Type
- Hole
- Grade
- IT7
- Tolerance
- 10 … 63 µm
- Fund. deviation
- ES −4 … −17 µm
N7 limits by size range
| Size (mm) | Upper (µm) | Lower (µm) | Ø max (mm) | Ø min (mm) | Upper (mm) | Lower (mm) | Dev. (in) |
|---|---|---|---|---|---|---|---|
| ≤ 3 | −4 | −14 | 2.996 | 2.986 | −0.004 | −0.014 | −0.00016 / −0.00055 |
| 3 – 6 | −4 | −16 | 5.996 | 5.984 | −0.004 | −0.016 | −0.00016 / −0.00063 |
| 6 – 10 | −4 | −19 | 9.996 | 9.981 | −0.004 | −0.019 | −0.00016 / −0.00075 |
| 10 – 14 | −5 | −23 | 13.995 | 13.977 | −0.005 | −0.023 | −0.00020 / −0.00091 |
| 14 – 18 | −5 | −23 | 17.995 | 17.977 | −0.005 | −0.023 | −0.00020 / −0.00091 |
| 18 – 24 | −7 | −28 | 23.993 | 23.972 | −0.007 | −0.028 | −0.00028 / −0.00110 |
| 24 – 30 | −7 | −28 | 29.993 | 29.972 | −0.007 | −0.028 | −0.00028 / −0.00110 |
| 30 – 40 | −8 | −33 | 39.992 | 39.967 | −0.008 | −0.033 | −0.00031 / −0.00130 |
| 40 – 50 | −8 | −33 | 49.992 | 49.967 | −0.008 | −0.033 | −0.00031 / −0.00130 |
| 50 – 65 | −9 | −39 | 64.991 | 64.961 | −0.009 | −0.039 | −0.00035 / −0.00154 |
| 65 – 80 | −9 | −39 | 79.991 | 79.961 | −0.009 | −0.039 | −0.00035 / −0.00154 |
| 80 – 100 | −10 | −45 | 99.990 | 99.955 | −0.010 | −0.045 | −0.00039 / −0.00177 |
| 100 – 120 | −10 | −45 | 119.990 | 119.955 | −0.010 | −0.045 | −0.00039 / −0.00177 |
| 120 – 140 | −12 | −52 | 139.988 | 139.948 | −0.012 | −0.052 | −0.00047 / −0.00205 |
| 140 – 160 | −12 | −52 | 159.988 | 159.948 | −0.012 | −0.052 | −0.00047 / −0.00205 |
| 160 – 180 | −12 | −52 | 179.988 | 179.948 | −0.012 | −0.052 | −0.00047 / −0.00205 |
| 180 – 200 | −14 | −60 | 199.986 | 199.940 | −0.014 | −0.060 | −0.00055 / −0.00236 |
| 200 – 225 | −14 | −60 | 224.986 | 224.940 | −0.014 | −0.060 | −0.00055 / −0.00236 |
| 225 – 250 | −14 | −60 | 249.986 | 249.940 | −0.014 | −0.060 | −0.00055 / −0.00236 |
| 250 – 280 | −14 | −66 | 279.986 | 279.934 | −0.014 | −0.066 | −0.00055 / −0.00260 |
| 280 – 315 | −14 | −66 | 314.986 | 314.934 | −0.014 | −0.066 | −0.00055 / −0.00260 |
| 315 – 355 | −16 | −73 | 354.984 | 354.927 | −0.016 | −0.073 | −0.00063 / −0.00287 |
| 355 – 400 | −16 | −73 | 399.984 | 399.927 | −0.016 | −0.073 | −0.00063 / −0.00287 |
| 400 – 450 | −17 | −80 | 449.983 | 449.920 | −0.017 | −0.080 | −0.00067 / −0.00315 |
| 450 – 500 | −17 | −80 | 499.983 | 499.920 | −0.017 | −0.080 | −0.00067 / −0.00315 |
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 N7
N7 denotes a hole tolerance zone with tight transition deviation in the ISO 286 system. It is used in N7/h6 (Shaft-basis equivalent of H7/n6; common for bearing outer rings under rotating outer-ring load.).
At Ø25 mm N7 is −0.007 / −0.028 mm, i.e. 24.972 to 24.993 mm.
How the limits are calculated
N7 uses grade IT7 (a standard tolerance of 21 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); IT7 sets the width below ES. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.