H8/u7 fit — Force fit

ISO 286 hole-basis interference fit. Enter a nominal size to get the limits.

Nominal size

Unit

Result

Ø25.000 H8/u7Interference fit

	Upper	Lower	Max	Min	Tol.
Hole H8	+0.033	0	25.033	25.000	0.033
Shaft u7	+0.069	+0.048	25.069	25.048	0.021

Max interference: 0.069 mm
Min interference: 0.015 mm
Mean: −0.042 mm

Fit diagram (µm · zero line = nominal)

Hole tolerance zoneShaft tolerance zoneInterference

About H8/u7

Coarser heavy press or shrink fit for permanent assemblies.

At Ø25 mm the hole H8 measures 0 mm to +0.033 mm and the shaft u7 +0.048 mm to +0.069 mm, giving an interference of 0.015 mm to 0.069 mm.

How the limits are calculated

Hole H8: fundamental deviation EI = 0, standard tolerance IT8 = 33 µm for 18–30 mm. Shaft u7: fundamental deviation ei = 48 µm, IT7 = 21 µm. Clearance = hole − shaft, evaluated at both extremes. Values per ISO 286-1:2010.

H8/u7 limits by size range

Size (mm)	Hole H8	Shaft u7	Clearance min	Clearance max
≤ 3	+0.014 / 0	+0.028 / +0.018	−0.028	−0.004
3 – 6	+0.018 / 0	+0.035 / +0.023	−0.035	−0.005
6 – 10	+0.022 / 0	+0.043 / +0.028	−0.043	−0.006
10 – 18	+0.027 / 0	+0.051 / +0.033	−0.051	−0.006
18 – 30	+0.033 / 0	+0.069 / +0.048	−0.069	−0.015
30 – 50	+0.039 / 0	+0.095 / +0.070	−0.095	−0.031
50 – 80	+0.046 / 0	+0.132 / +0.102	−0.132	−0.056
80 – 120	+0.054 / 0	+0.179 / +0.144	−0.179	−0.090
120 – 180	+0.063 / 0	+0.250 / +0.210	−0.250	−0.147
180 – 250	+0.072 / 0	+0.330 / +0.284	−0.330	−0.212
250 – 315	+0.081 / 0	+0.402 / +0.350	−0.402	−0.269
315 – 400	+0.089 / 0	+0.492 / +0.435	−0.492	−0.346
400 – 500	+0.097 / 0	+0.603 / +0.540	−0.603	−0.443

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.