SuperNX / Tools / ISO 286 fit calculator
ISO 286 Fit Calculator
| Member | Upper dev. | Lower dev. | Min size | Max size |
|---|---|---|---|---|
| Hole H7 (Ø) | +25 µm | 0 µm | 40.000 | 40.025 |
| Shaft g6 (Ø) | −9 µm | −25 µm | 39.975 | 39.991 |
| Resulting clearance | max +50 µm | min +9 µm | ||
Default shown: Ø40 H7/g6 — a classic sliding fit. Try Ø25 H7/k6 (transition) or H7/s6 (interference). Deviations in µm; sizes in mm. Hole letters: H, JS, plus E/F/G (clearance classes). Shaft letters: e f g h js k m n p r s, grades 5–12.
What the answer means
Every callout like Ø40 H7/g6 fixes two things: how wide each tolerance zone is (the IT grade number) and where it sits relative to the nominal size (the letter). The calculator resolves both to upper/lower deviations, then subtracts shaft limits from hole limits to get the clearance range.
- Clearance fit — min clearance ≥ 0: the parts always slip (running, sliding, locational clearance).
- Interference fit — max clearance ≤ 0: the parts always need force or heat (press, shrink, drive fits).
- Transition fit — the zones overlap: production parts may clear or press (accurate location with light assembly force).
For the full mental model — hole-basis vs shaft-basis, why H7 is the default hole, how to pick between g6, k6 and p6 — read ISO 286 fits explained. Worst-case thinking across whole chains: worst-case vs statistical tolerance analysis.
Data & provenance
All values come from the published ISO 286-1/-2 tables (IT grades IT5–IT12 × 13 nominal steps; shaft fundamental deviations for e f g h js k m n p r s; holes H, JS and E/F/G by the mirror rule). The same table is served as JSON at /data/iso-286.json — engineering reference values, verify against the current standard revision for production drawings.