Press fit tolerance — H7 interference fits by size
H7/p6 through H7/u6, Ø10 mm to Ø200 mm: minimum and maximum interference in millimetres, computed from ISO 286-1:2010.
Interference by size
| Size (mm) | H7/p6 | H7/s6 | ||
|---|---|---|---|---|
| min (mm) | max (mm) | min (mm) | max (mm) | |
| 10 | 0 | +0.024 | +0.008 | +0.032 |
| 20 | +0.001 | +0.035 | +0.014 | +0.048 |
| 25 | +0.001 | +0.035 | +0.014 | +0.048 |
| 30 | +0.001 | +0.035 | +0.014 | +0.048 |
| 40 | +0.001 | +0.042 | +0.018 | +0.059 |
| 50 | +0.001 | +0.042 | +0.018 | +0.059 |
| 80 | +0.002 | +0.051 | +0.029 | +0.078 |
| 100 | +0.002 | +0.059 | +0.036 | +0.093 |
| 150 | +0.003 | +0.068 | +0.060 | +0.125 |
| 200 | +0.004 | +0.079 | +0.076 | +0.151 |
Positive = interference; a negative value is clearance at that size. Deviations at the listed size; use the calculator for the exact size. r6 and u6 columns are shown on wider screens.
Which press fit
H7/p6 (locational interference) is the lightest of the four: enough to hold a bush or dowel without a key, but not enough to transmit meaningful torque on its own. H7/r6 and H7/s6 are medium drive fits — permanent joints (gear rims, bearing bushes, shaft-hub connections) that carry torque without a key and can still be pressed apart with tooling. H7/u6 is a heavy force fit for permanent, high-load assemblies; it typically needs the hub heated or the shaft cooled before assembly. Heavier still are H7/t6 and H7/x6.
Design checks
- Surface finish: a rough bore or shaft reduces the effective interference (asperities crush on assembly) — specify Ra and check it against the nominal interference, not just the size tolerance.
- Lead-in chamfer on both parts (typically 15–20°) so the shaft self-centres instead of galling the bore on entry.
- Hoop stress in the hub: a thin-wall hub can yield or crack under the pressure generated by the chosen interference — check wall thickness against material yield strength before specifying u6 or heavier.
- Thermal assembly: for the larger interferences (s6, u6) heating the hub or cooling the shaft reduces assembly force and avoids scoring; size the temperature change from the material's thermal expansion coefficient and the required diametral clearance for assembly.
Work out the interference for your own size and shaft in the calculator, or use the fit finder to search by clearance or interference target instead of class name.