H8/js7 fit — Locational transition
ISO 286 hole-basis transition fit. Enter a nominal size to get the limits.
About H8/js7
Symmetric transition fit (equal chance of clearance or interference) on an IT8 hole for lower-cost locational assemblies that still need accurate centring: fixture plates, coarse gear-on-shaft assemblies.
At Ø25 mm the hole H8 measures 0 mm to +0.033 mm and the shaft js7 −0.0105 mm to +0.0105 mm, giving between 0.0105 mm interference and 0.0435 mm clearance.
How the limits are calculated
Hole H8: fundamental deviation EI = 0, standard tolerance IT8 = 33 µm for 18–30 mm. Shaft js7: fundamental deviation ei = -10.5 µm, IT7 = 21 µm. Clearance = hole − shaft, evaluated at both extremes. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.
H8/js7 limits by size range
| Size (mm) | Hole H8 | Shaft js7 | Clearance min | Clearance max |
|---|---|---|---|---|
| ≤ 3 | +0.014 / 0 | +0.005 / −0.005 | −0.005 | +0.019 |
| 3 – 6 | +0.018 / 0 | +0.006 / −0.006 | −0.006 | +0.024 |
| 6 – 10 | +0.022 / 0 | +0.0075 / −0.0075 | −0.0075 | +0.0295 |
| 10 – 18 | +0.027 / 0 | +0.009 / −0.009 | −0.009 | +0.036 |
| 18 – 30 | +0.033 / 0 | +0.0105 / −0.0105 | −0.0105 | +0.0435 |
| 30 – 50 | +0.039 / 0 | +0.0125 / −0.0125 | −0.0125 | +0.0515 |
| 50 – 80 | +0.046 / 0 | +0.015 / −0.015 | −0.015 | +0.061 |
| 80 – 120 | +0.054 / 0 | +0.0175 / −0.0175 | −0.0175 | +0.0715 |
| 120 – 180 | +0.063 / 0 | +0.020 / −0.020 | −0.020 | +0.083 |
| 180 – 250 | +0.072 / 0 | +0.023 / −0.023 | −0.023 | +0.095 |
| 250 – 315 | +0.081 / 0 | +0.026 / −0.026 | −0.026 | +0.107 |
| 315 – 400 | +0.089 / 0 | +0.0285 / −0.0285 | −0.0285 | +0.1175 |
| 400 – 500 | +0.097 / 0 | +0.0315 / −0.0315 | −0.0315 | +0.1285 |
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/js7 a clearance fit?
Not always — H8/js7 is a transition fit per ISO 286 (see types of fits). At Ø25 mm it gives between 0.0105 mm mm interference and 0.0435 mm mm clearance, depending which parts of the tolerance zones are paired.
What is the H8/js7 tolerance at 25 mm?
At a nominal size of Ø25 mm, H8 allows a hole diameter from 25.000 to 25.033 mm, and js7 allows a shaft diameter from 24.9895 to 25.0105 mm.