--- type: "fit" designation: "N7/h6" hole: "N7" shaft: "h6" basis: "shaft" classification: "transition" role: "Tight transition, shaft basis." size_count: 13 standard: "ISO 286-1:2010, ISO 286-2:2010" verified: "August 1, 2026" url: https://shopmath.org/fits/n7-h6 --- # N7/h6 Fit — ISO 286 Transition Fit Limits by Nominal Size N7/h6 is a transition fit: at 25 mm nominal it gives 28 µm interference to 6 µm clearance. Tight transition, shaft basis. Depending on where each part lands in tolerance, the joint may end up with a small clearance or a small interference. - **Designation**: N7/h6 - **Hole tolerance**: N7 - **Shaft tolerance**: h6 - **Basis**: shaft basis - **Classification**: Transition fit - **Typical use**: Tight transition, shaft basis. - **Standard**: ISO 286-1:2010, ISO 286-2:2010 ## N7/h6 Hole and Shaft Limits by Nominal Size Limits in millimetres, clearances in micrometres. A negative clearance is interference — the shaft is larger than the hole and assembly needs force, heat or cold. | Nominal size | Hole min (mm) | Hole max (mm) | Shaft min (mm) | Shaft max (mm) | Min clearance (µm) | Max clearance (µm) | Result | | --- | --- | --- | --- | --- | --- | --- | --- | | 5 mm | 4.984 | 4.996 | 4.992 | 5.000 | -16 | 4 | Transition | | 6 mm | 5.984 | 5.996 | 5.992 | 6.000 | -16 | 4 | Transition | | 8 mm | 7.981 | 7.996 | 7.991 | 8.000 | -19 | 5 | Transition | | 10 mm | 9.981 | 9.996 | 9.991 | 10.000 | -19 | 5 | Transition | | 12 mm | 11.977 | 11.995 | 11.989 | 12.000 | -23 | 6 | Transition | | 16 mm | 15.977 | 15.995 | 15.989 | 16.000 | -23 | 6 | Transition | | 20 mm | 19.972 | 19.993 | 19.987 | 20.000 | -28 | 6 | Transition | | 25 mm | 24.972 | 24.993 | 24.987 | 25.000 | -28 | 6 | Transition | | 30 mm | 29.972 | 29.993 | 29.987 | 30.000 | -28 | 6 | Transition | | 40 mm | 39.967 | 39.992 | 39.984 | 40.000 | -33 | 8 | Transition | | 50 mm | 49.967 | 49.992 | 49.984 | 50.000 | -33 | 8 | Transition | | 80 mm | 79.961 | 79.991 | 79.981 | 80.000 | -39 | 10 | Transition | | 100 mm | 99.955 | 99.990 | 99.978 | 100.000 | -45 | 12 | Transition | ## Fits Related to N7/h6 Fits that share the N7 hole or the h6 shaft — the alternatives to reach for when N7/h6 is too tight or too loose. | Fit | Classification | Basis | Typical use | | --- | --- | --- | --- | | [G7/h6](https://shopmath.org/fits/g7-h6.md) | Clearance | shaft basis | Sliding, shaft basis. The h6 shaft is the reference and the hole carries the clearance. | | [H7/h6](https://shopmath.org/fits/h7-h6.md) | Clearance | both basis | Locational clearance. Assembles by hand, no free movement intended. | | [P7/h6](https://shopmath.org/fits/p7-h6.md) | Interference | shaft basis | Locational interference, shaft basis. | | [K7/h6](https://shopmath.org/fits/k7-h6.md) | Transition | shaft basis | Locational transition, shaft basis. | ## Sources and Method for the N7/h6 Fit ### N7/h6 limits - **Source**: computed from the compiled ISO 286 tables: ISO 286-1 IT grades and ISO 286-2 fundamental deviations, compiled from saucecode/ISO286 (LGPL-2.1) and parkergreene/isofits (MIT), cross-checked cell-for-cell - **Method**: computed - **Verified against**: parkergreene/isofits ISO 286-2 limit tables (MIT); ISO 286-1 formula harness — 2067 checks passed ### Assumptions - Values are the ISO 286-2 tabulated limits, not the ISO 286-1 formula: the formula deviates from the table by up to 13.26% and is carried only as a validation harness. - Limits are at 20 °C, the ISO 1 reference temperature. Clearance is the assembled gap before any thermal or load effect. - Dataset scope: COMPILED not computed: the ISO 286-1 formula deviates up to 13.26% from the table and is used only as a harness (warn >5%, fail >15%). EXCLUDED: shaft/hole letters s, t, u and the fits H7/s6, H7/t6, H7/u6 — no free source and an undetermined step constant in the formula. **Data last verified**: August 1, 2026 ## Common Questions About the N7/h6 Fit ### What kind of fit is N7/h6? N7/h6 is a transition fit on a shaft basis. Depending on where each part lands in tolerance, the joint may end up with a small clearance or a small interference. Tight transition, shaft basis. ### What is the clearance on a 25 mm N7/h6 fit? At 25 mm nominal, N7/h6 gives 28 µm interference to 6 µm clearance. The hole runs 24.972 to 24.993 mm and the shaft 24.987 to 25.000 mm. ### What hole and shaft tolerances make up N7/h6? N7/h6 pairs a N7 hole with a h6 shaft. On a shaft basis, the shaft carries the zero-deviation member and the other side is moved to set the fit. ## Related pages - Hole tolerance: [N7 limits by size](https://shopmath.org/fits/n7.md) - Shaft tolerance: [h6 limits by size](https://shopmath.org/fits/h6.md) - All fits and tolerances: [ISO 286 fit reference](https://shopmath.org/fits.md) - Full grade table: [ISO 286 tolerance chart](https://shopmath.org/charts/iso-tolerances.md) --- *Source: [ShopMath](https://shopmath.org/fits/n7-h6) — data verified August 1, 2026. Reference data; verify against the governing standard before manufacture.*