H8/f7 fit — Close running fit

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

Nominal size

Unit

Result

Ø25.000 H8/f7Clearance fit

	Upper	Lower	Max	Min	Tol.
Hole H8	+0.033	0	25.033	25.000	0.033
Shaft f7	−0.020	−0.041	24.980	24.959	0.021

Max clearance: 0.074 mm
Min clearance: 0.020 mm
Mean: +0.047 mm

Fit diagram (µm · zero line = nominal)

Hole tolerance zoneShaft tolerance zoneClearance

About H8/f7

Accurate machines and shafts in plain bearings at moderate speeds and pressures: machine tool spindles, gearbox shafts.

At Ø25 mm the hole H8 measures 0 mm to +0.033 mm and the shaft f7 −0.041 mm to −0.020 mm, giving a clearance of 0.020 mm to 0.074 mm.

How the limits are calculated

Hole H8: fundamental deviation EI = 0, standard tolerance IT8 = 33 µm for 18–30 mm. Shaft f7: fundamental deviation es = -20 µm, IT7 = 21 µm. Clearance = hole − shaft, evaluated at both extremes. Values per ISO 286-1:2010.

H8/f7 limits by size range

Size (mm)	Hole H8	Shaft f7	Clearance min	Clearance max
≤ 3	+0.014 / 0	−0.006 / −0.016	+0.006	+0.030
3 – 6	+0.018 / 0	−0.010 / −0.022	+0.010	+0.040
6 – 10	+0.022 / 0	−0.013 / −0.028	+0.013	+0.050
10 – 18	+0.027 / 0	−0.016 / −0.034	+0.016	+0.061
18 – 30	+0.033 / 0	−0.020 / −0.041	+0.020	+0.074
30 – 50	+0.039 / 0	−0.025 / −0.050	+0.025	+0.089
50 – 80	+0.046 / 0	−0.030 / −0.060	+0.030	+0.106
80 – 120	+0.054 / 0	−0.036 / −0.071	+0.036	+0.125
120 – 180	+0.063 / 0	−0.043 / −0.083	+0.043	+0.146
180 – 250	+0.072 / 0	−0.050 / −0.096	+0.050	+0.168
250 – 315	+0.081 / 0	−0.056 / −0.108	+0.056	+0.189
315 – 400	+0.089 / 0	−0.062 / −0.119	+0.062	+0.208
400 – 500	+0.097 / 0	−0.068 / −0.131	+0.068	+0.228

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.