---
type: "fit-designation"
designation: "g6"
letter: "g"
it_grade: "ITIT6"
feature: "shaft"
role: "Sliding shaft with minimal clearance — locates accurately and still moves freely."
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/g6
---

# g6 Tolerance — ISO 286 Shaft Limits by Nominal Size

A 25 mm g6 shaft runs 24.980 to 24.993 mm — deviations -20 to -7 µm on a 13 µm band. g6 is the ISO 286 shaft tolerance built from fundamental deviation g and standard tolerance grade ITIT6. Sliding shaft with minimal clearance — locates accurately and still moves freely.

- **Designation**: g6
- **Feature**: shaft
- **Fundamental deviation**: g — Sliding, small clearance
- **Tolerance grade**: ITIT6
- **Typical use**: Sliding shaft with minimal clearance — locates accurately and still moves freely.
- **Standard**: ISO 286-1:2010, ISO 286-2:2010

## g6 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/g6/5mm.md) | -4 | -12 | 4.988 | 4.996 | 8 |
| [6 mm](https://shopmath.org/fits/g6/6mm.md) | -4 | -12 | 5.988 | 5.996 | 8 |
| [8 mm](https://shopmath.org/fits/g6/8mm.md) | -5 | -14 | 7.986 | 7.995 | 9 |
| [10 mm](https://shopmath.org/fits/g6/10mm.md) | -5 | -14 | 9.986 | 9.995 | 9 |
| [12 mm](https://shopmath.org/fits/g6/12mm.md) | -6 | -17 | 11.983 | 11.994 | 11 |
| [16 mm](https://shopmath.org/fits/g6/16mm.md) | -6 | -17 | 15.983 | 15.994 | 11 |
| [20 mm](https://shopmath.org/fits/g6/20mm.md) | -7 | -20 | 19.980 | 19.993 | 13 |
| [25 mm](https://shopmath.org/fits/g6/25mm.md) | -7 | -20 | 24.980 | 24.993 | 13 |
| [30 mm](https://shopmath.org/fits/g6/30mm.md) | -7 | -20 | 29.980 | 29.993 | 13 |
| [40 mm](https://shopmath.org/fits/g6/40mm.md) | -9 | -25 | 39.975 | 39.991 | 16 |
| [50 mm](https://shopmath.org/fits/g6/50mm.md) | -9 | -25 | 49.975 | 49.991 | 16 |
| [80 mm](https://shopmath.org/fits/g6/80mm.md) | -10 | -29 | 79.971 | 79.990 | 19 |
| [100 mm](https://shopmath.org/fits/g6/100mm.md) | -12 | -34 | 99.966 | 99.988 | 22 |

_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 g6

### g6 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 g6 Tolerance

### What is an g6 tolerance?

g6 is an ISO 286 shaft tolerance: fundamental deviation g at IT grade IT6. Sliding shaft with minimal clearance — locates accurately and still moves freely. Sliding, small clearance describes what the g deviation does.

### What is the tolerance on a 25 mm g6 shaft?

A 25 mm g6 shaft runs 24.980 to 24.993 mm — deviations -20 to -7 µm, a tolerance band of 13 µm.

## Fits Built on g6

Standard hole/shaft pairs that use g6 as their shaft.

| Fit | Classification | Basis | Typical use |
| --- | --- | --- | --- |
| [H7/g6](https://shopmath.org/fits/h7-g6.md) | Clearance | hole basis | Sliding. Locates accurately, still moves and turns freely. |

## 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/g6) — data verified August 1, 2026. Reference data; verify against the governing standard before manufacture.*