H8/h8 fit — Locational clearance
ISO 286 hole-basis clearance fit. Enter a nominal size to get the limits.
About H8/h8
General-purpose sliding and locating fit for parts that need to move freely but stay aligned.
At Ø25 mm the hole H8 measures 0 mm to +0.033 mm and the shaft h8 −0.033 mm to 0 mm, giving a clearance of 0.000 mm to 0.066 mm.
How the limits are calculated
Hole H8: fundamental deviation EI = 0, standard tolerance IT8 = 33 µm for 18–30 mm. Shaft h8: fundamental deviation es = 0, IT8 = 33 µm. Clearance = hole − shaft, evaluated at both extremes. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.
H8/h8 limits by size range
| Size (mm) | Hole H8 | Shaft h8 | Clearance min | Clearance max |
|---|---|---|---|---|
| ≤ 3 | +0.014 / 0 | 0 / −0.014 | 0 | +0.028 |
| 3 – 6 | +0.018 / 0 | 0 / −0.018 | 0 | +0.036 |
| 6 – 10 | +0.022 / 0 | 0 / −0.022 | 0 | +0.044 |
| 10 – 18 | +0.027 / 0 | 0 / −0.027 | 0 | +0.054 |
| 18 – 30 | +0.033 / 0 | 0 / −0.033 | 0 | +0.066 |
| 30 – 50 | +0.039 / 0 | 0 / −0.039 | 0 | +0.078 |
| 50 – 80 | +0.046 / 0 | 0 / −0.046 | 0 | +0.092 |
| 80 – 120 | +0.054 / 0 | 0 / −0.054 | 0 | +0.108 |
| 120 – 180 | +0.063 / 0 | 0 / −0.063 | 0 | +0.126 |
| 180 – 250 | +0.072 / 0 | 0 / −0.072 | 0 | +0.144 |
| 250 – 315 | +0.081 / 0 | 0 / −0.081 | 0 | +0.162 |
| 315 – 400 | +0.089 / 0 | 0 / −0.089 | 0 | +0.178 |
| 400 – 500 | +0.097 / 0 | 0 / −0.097 | 0 | +0.194 |
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/h8 a clearance fit?
Yes — H8/h8 is a clearance fit per ISO 286 (see types of fits). At Ø25 mm it gives a clearance of 0.000 mm to 0.066 mm mm, depending which parts of the tolerance zones are paired.
What is the H8/h8 tolerance at 25 mm?
At a nominal size of Ø25 mm, H8 allows a hole diameter from 25.000 to 25.033 mm, and h8 allows a shaft diameter from 24.967 to 25.000 mm.