H8/p7 fit — Locational transition
ISO 286 hole-basis transition fit. Enter a nominal size to get the limits.
About H8/p7
Coarser than H7/p7, on an IT8 hole; lands as a light interference or a very tight clearance, used where full H7/p6-class precision isn't justified but the joint must not move in service. See press fit tolerance for interference by size across the p6–u6 family.
At Ø25 mm the hole H8 measures 0 mm to +0.033 mm and the shaft p7 +0.022 mm to +0.043 mm, giving between 0.043 mm interference and 0.011 mm clearance.
How the limits are calculated
Hole H8: fundamental deviation EI = 0, standard tolerance IT8 = 33 µm for 18–30 mm. Shaft p7: fundamental deviation ei = 22 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.
H8/p7 limits by size range
| Size (mm) | Hole H8 | Shaft p7 | Clearance min | Clearance max |
|---|---|---|---|---|
| ≤ 3 | +0.014 / 0 | +0.016 / +0.006 | −0.016 | +0.008 |
| 3 – 6 | +0.018 / 0 | +0.024 / +0.012 | −0.024 | +0.006 |
| 6 – 10 | +0.022 / 0 | +0.030 / +0.015 | −0.030 | +0.007 |
| 10 – 18 | +0.027 / 0 | +0.036 / +0.018 | −0.036 | +0.009 |
| 18 – 30 | +0.033 / 0 | +0.043 / +0.022 | −0.043 | +0.011 |
| 30 – 50 | +0.039 / 0 | +0.051 / +0.026 | −0.051 | +0.013 |
| 50 – 80 | +0.046 / 0 | +0.062 / +0.032 | −0.062 | +0.014 |
| 80 – 120 | +0.054 / 0 | +0.072 / +0.037 | −0.072 | +0.017 |
| 120 – 180 | +0.063 / 0 | +0.083 / +0.043 | −0.083 | +0.020 |
| 180 – 250 | +0.072 / 0 | +0.096 / +0.050 | −0.096 | +0.022 |
| 250 – 315 | +0.081 / 0 | +0.108 / +0.056 | −0.108 | +0.025 |
| 315 – 400 | +0.089 / 0 | +0.119 / +0.062 | −0.119 | +0.027 |
| 400 – 500 | +0.097 / 0 | +0.131 / +0.068 | −0.131 | +0.029 |
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 H8/p7 a clearance fit?
Not always — H8/p7 is a transition fit per ISO 286 (see types of fits). At Ø25 mm it gives between 0.043 mm mm interference and 0.011 mm mm clearance, depending which parts of the tolerance zones are paired.
What is the H8/p7 tolerance at 25 mm?
At a nominal size of Ø25 mm, H8 allows a hole diameter from 25.000 to 25.033 mm, and p7 allows a shaft diameter from 25.022 to 25.043 mm.