H7/k6 fit — Locational transition

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

Nominal size

Unit

Result

Ø25.000 H7/k6Transition fit

	Upper	Lower	Max	Min	Tol.
Hole H7	+0.021	0	25.021	25.000	0.021
Shaft k6	+0.015	+0.002	25.015	25.002	0.013

Max clearance: 0.019 mm
Max interference: 0.015 mm
Mean: +0.002 mm

Fit diagram (µm · zero line = nominal)

Hole tolerance zoneShaft tolerance zoneClearanceInterference

About H7/k6

The standard "push fit" for gears, pulleys and ball-bearing inner rings on shafts; assembles with a light press or mallet, transmits torque only with a key.

At Ø25 mm the hole H7 measures 0 mm to +0.021 mm and the shaft k6 +0.002 mm to +0.015 mm, giving between 0.015 mm interference and 0.019 mm clearance.

How the limits are calculated

Hole H7: fundamental deviation EI = 0, standard tolerance IT7 = 21 µm for 18–30 mm. Shaft k6: fundamental deviation ei = 2 µm, IT6 = 13 µm. Clearance = hole − shaft, evaluated at both extremes. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.

H7/k6 limits by size range

Size (mm)	Hole H7	Shaft k6	Clearance min	Clearance max
≤ 3	+0.010 / 0	+0.006 / 0	−0.006	+0.010
3 – 6	+0.012 / 0	+0.009 / +0.001	−0.009	+0.011
6 – 10	+0.015 / 0	+0.010 / +0.001	−0.010	+0.014
10 – 18	+0.018 / 0	+0.012 / +0.001	−0.012	+0.017
18 – 30	+0.021 / 0	+0.015 / +0.002	−0.015	+0.019
30 – 50	+0.025 / 0	+0.018 / +0.002	−0.018	+0.023
50 – 80	+0.030 / 0	+0.021 / +0.002	−0.021	+0.028
80 – 120	+0.035 / 0	+0.025 / +0.003	−0.025	+0.032
120 – 180	+0.040 / 0	+0.028 / +0.003	−0.028	+0.037
180 – 250	+0.046 / 0	+0.033 / +0.004	−0.033	+0.042
250 – 315	+0.052 / 0	+0.036 / +0.004	−0.036	+0.048
315 – 400	+0.057 / 0	+0.040 / +0.004	−0.040	+0.053
400 – 500	+0.063 / 0	+0.045 / +0.005	−0.045	+0.058

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 H7/k6 a clearance fit?

Not always — H7/k6 is a transition fit per ISO 286 (see types of fits). At Ø25 mm it gives between 0.015 mm mm interference and 0.019 mm mm clearance, depending which parts of the tolerance zones are paired.

What is the H7/k6 tolerance at 25 mm?

At a nominal size of Ø25 mm, H7 allows a hole diameter from 25.000 to 25.021 mm, and k6 allows a shaft diameter from 25.002 to 25.015 mm.