H7/u6 fit — Force fit

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

Nominal size

Unit

Result

Ø25.000 H7/u6Interference fit

	Upper	Lower	Max	Min	Tol.
Hole H7	+0.021	0	25.021	25.000	0.021
Shaft u6	+0.061	+0.048	25.061	25.048	0.013

Max interference: 0.061 mm
Min interference: 0.027 mm
Mean: −0.044 mm

Fit diagram (µm · zero line = nominal)

Hole tolerance zoneShaft tolerance zoneInterference

About H7/u6

Heavy press or shrink fit for permanent assemblies under high load; requires heating the hub or cooling the shaft.

At Ø25 mm the hole H7 measures 0 mm to +0.021 mm and the shaft u6 +0.048 mm to +0.061 mm, giving an interference of 0.027 mm to 0.061 mm.

How the limits are calculated

Hole H7: fundamental deviation EI = 0, standard tolerance IT7 = 21 µm for 18–30 mm. Shaft u6: fundamental deviation ei = 48 µm, IT6 = 13 µm. Clearance = hole − shaft, evaluated at both extremes. Values per ISO 286-1:2010.

H7/u6 limits by size range

Size (mm)	Hole H7	Shaft u6	Clearance min	Clearance max
≤ 3	+0.010 / 0	+0.024 / +0.018	−0.024	−0.008
3 – 6	+0.012 / 0	+0.031 / +0.023	−0.031	−0.011
6 – 10	+0.015 / 0	+0.037 / +0.028	−0.037	−0.013
10 – 18	+0.018 / 0	+0.044 / +0.033	−0.044	−0.015
18 – 30	+0.021 / 0	+0.061 / +0.048	−0.061	−0.027
30 – 50	+0.025 / 0	+0.086 / +0.070	−0.086	−0.045
50 – 80	+0.030 / 0	+0.121 / +0.102	−0.121	−0.072
80 – 120	+0.035 / 0	+0.166 / +0.144	−0.166	−0.109
120 – 180	+0.040 / 0	+0.235 / +0.210	−0.235	−0.170
180 – 250	+0.046 / 0	+0.313 / +0.284	−0.313	−0.238
250 – 315	+0.052 / 0	+0.382 / +0.350	−0.382	−0.298
315 – 400	+0.057 / 0	+0.471 / +0.435	−0.471	−0.378
400 – 500	+0.063 / 0	+0.580 / +0.540	−0.580	−0.477

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.