H7/n7 fit — Locational transition
ISO 286 hole-basis transition fit. Enter a nominal size to get the limits.
About 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.
At Ø25 mm the hole H7 measures 0 mm to +0.021 mm and the shaft n7 +0.015 mm to +0.036 mm, giving between 0.036 mm interference and 0.006 mm clearance.
How the limits are calculated
Hole H7: fundamental deviation EI = 0, standard tolerance IT7 = 21 µm for 18–30 mm. Shaft n7: fundamental deviation ei = 15 µm, IT7 = 21 µm. Clearance = hole − shaft, evaluated at both extremes. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.
H7/n7 limits by size range
| Size (mm) | Hole H7 | Shaft n7 | Clearance min | Clearance max |
|---|---|---|---|---|
| ≤ 3 | +0.010 / 0 | +0.014 / +0.004 | −0.014 | +0.006 |
| 3 – 6 | +0.012 / 0 | +0.020 / +0.008 | −0.020 | +0.004 |
| 6 – 10 | +0.015 / 0 | +0.025 / +0.010 | −0.025 | +0.005 |
| 10 – 18 | +0.018 / 0 | +0.030 / +0.012 | −0.030 | +0.006 |
| 18 – 30 | +0.021 / 0 | +0.036 / +0.015 | −0.036 | +0.006 |
| 30 – 50 | +0.025 / 0 | +0.042 / +0.017 | −0.042 | +0.008 |
| 50 – 80 | +0.030 / 0 | +0.050 / +0.020 | −0.050 | +0.010 |
| 80 – 120 | +0.035 / 0 | +0.058 / +0.023 | −0.058 | +0.012 |
| 120 – 180 | +0.040 / 0 | +0.067 / +0.027 | −0.067 | +0.013 |
| 180 – 250 | +0.046 / 0 | +0.077 / +0.031 | −0.077 | +0.015 |
| 250 – 315 | +0.052 / 0 | +0.086 / +0.034 | −0.086 | +0.018 |
| 315 – 400 | +0.057 / 0 | +0.094 / +0.037 | −0.094 | +0.020 |
| 400 – 500 | +0.063 / 0 | +0.103 / +0.040 | −0.103 | +0.023 |
Deviations in mm at the upper end of each range; negative clearance = interference. Clearance columns are shown on wider screens. Sub-ranges (e.g. 18–24 / 24–30) can differ for r, s, t, u, v, x, y, z — use the calculator for the exact size. “—” means ISO 286 doesn't define this class below that size (e.g. t only starts at 24 mm).
Is H7/n7 a clearance fit?
Not always — H7/n7 is a transition fit per ISO 286 (see types of fits). At Ø25 mm it gives between 0.036 mm mm interference and 0.006 mm mm clearance, depending which parts of the tolerance zones are paired.
What is the H7/n7 tolerance at 25 mm?
At a nominal size of Ø25 mm, H7 allows a hole diameter from 25.000 to 25.021 mm, and n7 allows a shaft diameter from 25.015 to 25.036 mm.