n7 tolerance (shaft, IT7)
Shaft tolerance class n7 per ISO 286-1:2010: fundamental deviation ei +4 … +40, 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
- Shaft
- Grade
- IT7
- Tolerance
- 10 … 63 µm
- Fund. deviation
- ei +4 … +40 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 | +14 | +4 | 3.014 | 3.004 | +0.014 | +0.004 | +0.00055 / +0.00016 |
| 3 – 6 | +20 | +8 | 6.020 | 6.008 | +0.020 | +0.008 | +0.00079 / +0.00031 |
| 6 – 10 | +25 | +10 | 10.025 | 10.010 | +0.025 | +0.010 | +0.00098 / +0.00039 |
| 10 – 14 | +30 | +12 | 14.030 | 14.012 | +0.030 | +0.012 | +0.00118 / +0.00047 |
| 14 – 18 | +30 | +12 | 18.030 | 18.012 | +0.030 | +0.012 | +0.00118 / +0.00047 |
| 18 – 24 | +36 | +15 | 24.036 | 24.015 | +0.036 | +0.015 | +0.00142 / +0.00059 |
| 24 – 30 | +36 | +15 | 30.036 | 30.015 | +0.036 | +0.015 | +0.00142 / +0.00059 |
| 30 – 40 | +42 | +17 | 40.042 | 40.017 | +0.042 | +0.017 | +0.00165 / +0.00067 |
| 40 – 50 | +42 | +17 | 50.042 | 50.017 | +0.042 | +0.017 | +0.00165 / +0.00067 |
| 50 – 65 | +50 | +20 | 65.050 | 65.020 | +0.050 | +0.020 | +0.00197 / +0.00079 |
| 65 – 80 | +50 | +20 | 80.050 | 80.020 | +0.050 | +0.020 | +0.00197 / +0.00079 |
| 80 – 100 | +58 | +23 | 100.058 | 100.023 | +0.058 | +0.023 | +0.00228 / +0.00091 |
| 100 – 120 | +58 | +23 | 120.058 | 120.023 | +0.058 | +0.023 | +0.00228 / +0.00091 |
| 120 – 140 | +67 | +27 | 140.067 | 140.027 | +0.067 | +0.027 | +0.00264 / +0.00106 |
| 140 – 160 | +67 | +27 | 160.067 | 160.027 | +0.067 | +0.027 | +0.00264 / +0.00106 |
| 160 – 180 | +67 | +27 | 180.067 | 180.027 | +0.067 | +0.027 | +0.00264 / +0.00106 |
| 180 – 200 | +77 | +31 | 200.077 | 200.031 | +0.077 | +0.031 | +0.00303 / +0.00122 |
| 200 – 225 | +77 | +31 | 225.077 | 225.031 | +0.077 | +0.031 | +0.00303 / +0.00122 |
| 225 – 250 | +77 | +31 | 250.077 | 250.031 | +0.077 | +0.031 | +0.00303 / +0.00122 |
| 250 – 280 | +86 | +34 | 280.086 | 280.034 | +0.086 | +0.034 | +0.00339 / +0.00134 |
| 280 – 315 | +86 | +34 | 315.086 | 315.034 | +0.086 | +0.034 | +0.00339 / +0.00134 |
| 315 – 355 | +94 | +37 | 355.094 | 355.037 | +0.094 | +0.037 | +0.00370 / +0.00146 |
| 355 – 400 | +94 | +37 | 400.094 | 400.037 | +0.094 | +0.037 | +0.00370 / +0.00146 |
| 400 – 450 | +103 | +40 | 450.103 | 450.040 | +0.103 | +0.040 | +0.00406 / +0.00157 |
| 450 – 500 | +103 | +40 | 500.103 | 500.040 | +0.103 | +0.040 | +0.00406 / +0.00157 |
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 shaft tolerance zone with tight transition deviation in the ISO 286 system. It is used in H7/n7 (Coarser than H7/n6 for firm, press-assembled locational fits on an IT7 hole: gear rims on hubs, bushings in cast housings, parts that are rarely dismantled.) and H8/n7 (Firm, near-interference transition fit on an IT8 hole; parts are rarely dismantled once pressed together, e.g. bearing bushes and gear hubs in cost-driven designs.).
At Ø25 mm n7 is +0.036 / +0.015 mm, i.e. 25.015 to 25.036 mm.
How the limits are calculated
n7 uses grade IT7 (a standard tolerance of 21 µm at 18–30 mm). Fundamental deviation: ei is tabulated directly by ISO 286-1 Table 2; es = ei + IT7. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.