---
type: "fit-designation"
designation: "h7"
letter: "h"
it_grade: "ITIT7"
feature: "shaft"
role: "Basic shaft one grade coarser than h6, for shaft-basis close running fits."
size_count: 13
size_range_mm: "5–100"
standard: "ISO 286-1:2010, ISO 286-2:2010"
verified: "August 1, 2026"
url: https://shopmath.org/fits/h7-shaft
---

# h7 Tolerance — ISO 286 Shaft Limits by Nominal Size

A 25 mm h7 shaft runs 24.979 to 25.000 mm — deviations -21 to +0 µm on a 21 µm band. h7 is the ISO 286 shaft tolerance built from fundamental deviation h and standard tolerance grade ITIT7. Basic shaft one grade coarser than h6, for shaft-basis close running fits.

- **Designation**: h7
- **Feature**: shaft
- **Fundamental deviation**: h — Zero deviation — the basic shaft
- **Tolerance grade**: ITIT7
- **Typical use**: Basic shaft one grade coarser than h6, for shaft-basis close running fits.
- **Standard**: ISO 286-1:2010, ISO 286-2:2010

## h7 Limits and Deviations by Nominal Size

Deviations are in micrometres from the nominal size; limits are the finished diameters in millimetres. Sizes that carry their own page are linked.

| Nominal size | Upper deviation (µm) | Lower deviation (µm) | Min shaft Ø (mm) | Max shaft Ø (mm) | IT tolerance (µm) |
| --- | --- | --- | --- | --- | --- |
| [5 mm](https://shopmath.org/fits/h7-shaft/5mm.md) | +0 | -12 | 4.988 | 5.000 | 12 |
| [6 mm](https://shopmath.org/fits/h7-shaft/6mm.md) | +0 | -12 | 5.988 | 6.000 | 12 |
| [8 mm](https://shopmath.org/fits/h7-shaft/8mm.md) | +0 | -15 | 7.985 | 8.000 | 15 |
| [10 mm](https://shopmath.org/fits/h7-shaft/10mm.md) | +0 | -15 | 9.985 | 10.000 | 15 |
| [12 mm](https://shopmath.org/fits/h7-shaft/12mm.md) | +0 | -18 | 11.982 | 12.000 | 18 |
| [16 mm](https://shopmath.org/fits/h7-shaft/16mm.md) | +0 | -18 | 15.982 | 16.000 | 18 |
| [20 mm](https://shopmath.org/fits/h7-shaft/20mm.md) | +0 | -21 | 19.979 | 20.000 | 21 |
| [25 mm](https://shopmath.org/fits/h7-shaft/25mm.md) | +0 | -21 | 24.979 | 25.000 | 21 |
| [30 mm](https://shopmath.org/fits/h7-shaft/30mm.md) | +0 | -21 | 29.979 | 30.000 | 21 |
| [40 mm](https://shopmath.org/fits/h7-shaft/40mm.md) | +0 | -25 | 39.975 | 40.000 | 25 |
| [50 mm](https://shopmath.org/fits/h7-shaft/50mm.md) | +0 | -25 | 49.975 | 50.000 | 25 |
| [80 mm](https://shopmath.org/fits/h7-shaft/80mm.md) | +0 | -30 | 79.970 | 80.000 | 30 |
| [100 mm](https://shopmath.org/fits/h7-shaft/100mm.md) | +0 | -35 | 99.965 | 100.000 | 35 |

_ISO 286 tabulates deviations per size band, so a value holds across the whole band a nominal size falls in, not just at that exact diameter._

## Sources and Method for h7

### h7 deviations

- **Source**: limits 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.
- 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 h7 Tolerance

### What is an h7 tolerance?

h7 is an ISO 286 shaft tolerance: fundamental deviation h at IT grade IT7. Basic shaft one grade coarser than h6, for shaft-basis close running fits. Zero deviation — the basic shaft describes what the h deviation does.

### What is the tolerance on a 25 mm h7 shaft?

A 25 mm h7 shaft runs 24.979 to 25.000 mm — deviations -21 to +0 µm, a tolerance band of 21 µm.

## Fits Built on h7

Standard hole/shaft pairs that use h7 as their shaft.

| Fit | Classification | Basis | Typical use |
| --- | --- | --- | --- |
| [F8/h7](https://shopmath.org/fits/f8-h7.md) | Clearance | shaft basis | Close running, shaft basis. |

## Related pages

- 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/h7-shaft) — data verified August 1, 2026. Reference data; verify against the governing standard before manufacture.*