H8/e9 fit — Free running fit
ISO 286 hole-basis clearance fit. Enter a nominal size to get the limits.
About H8/e9
Free-running plain-bearing fit for shafts made to a coarser IT9 grade, used where H9/e9-class play is acceptable but the housing bore needs the tighter IT8 tolerance.
At Ø25 mm the hole H8 measures 0 mm to +0.033 mm and the shaft e9 −0.092 mm to −0.040 mm, giving a clearance of 0.040 mm to 0.125 mm.
How the limits are calculated
Hole H8: fundamental deviation EI = 0, standard tolerance IT8 = 33 µm for 18–30 mm. Shaft e9: fundamental deviation es = -40 µm, IT9 = 52 µm. Clearance = hole − shaft, evaluated at both extremes. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.
H8/e9 limits by size range
| Size (mm) | Hole H8 | Shaft e9 | Clearance min | Clearance max |
|---|---|---|---|---|
| ≤ 3 | +0.014 / 0 | −0.014 / −0.039 | +0.014 | +0.053 |
| 3 – 6 | +0.018 / 0 | −0.020 / −0.050 | +0.020 | +0.068 |
| 6 – 10 | +0.022 / 0 | −0.025 / −0.061 | +0.025 | +0.083 |
| 10 – 18 | +0.027 / 0 | −0.032 / −0.075 | +0.032 | +0.102 |
| 18 – 30 | +0.033 / 0 | −0.040 / −0.092 | +0.040 | +0.125 |
| 30 – 50 | +0.039 / 0 | −0.050 / −0.112 | +0.050 | +0.151 |
| 50 – 80 | +0.046 / 0 | −0.060 / −0.134 | +0.060 | +0.180 |
| 80 – 120 | +0.054 / 0 | −0.072 / −0.159 | +0.072 | +0.213 |
| 120 – 180 | +0.063 / 0 | −0.085 / −0.185 | +0.085 | +0.248 |
| 180 – 250 | +0.072 / 0 | −0.100 / −0.215 | +0.100 | +0.287 |
| 250 – 315 | +0.081 / 0 | −0.110 / −0.240 | +0.110 | +0.321 |
| 315 – 400 | +0.089 / 0 | −0.125 / −0.265 | +0.125 | +0.354 |
| 400 – 500 | +0.097 / 0 | −0.135 / −0.290 | +0.135 | +0.387 |
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/e9 a clearance fit?
Yes — H8/e9 is a clearance fit per ISO 286 (see types of fits). At Ø25 mm it gives a clearance of 0.040 mm to 0.125 mm mm, depending which parts of the tolerance zones are paired.
What is the H8/e9 tolerance at 25 mm?
At a nominal size of Ø25 mm, H8 allows a hole diameter from 25.000 to 25.033 mm, and e9 allows a shaft diameter from 24.908 to 24.960 mm.