---
type: "fit-designation"
designation: "F8"
letter: "F"
it_grade: "ITIT8"
feature: "hole"
role: "Close running hole for shaft-basis fits with lubrication."
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/f8
---

# F8 Tolerance — ISO 286 Hole Limits by Nominal Size

A 25 mm F8 hole runs 25.020 to 25.053 mm — deviations +20 to +53 µm on a 33 µm band. F8 is the ISO 286 hole tolerance built from fundamental deviation F and standard tolerance grade ITIT8. Close running hole for shaft-basis fits with lubrication.

- **Designation**: F8
- **Feature**: hole
- **Fundamental deviation**: F — Close running clearance
- **Tolerance grade**: ITIT8
- **Typical use**: Close running hole for shaft-basis fits with lubrication.
- **Standard**: ISO 286-1:2010, ISO 286-2:2010

## F8 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 hole Ø (mm) | Max hole Ø (mm) | IT tolerance (µm) |
| --- | --- | --- | --- | --- | --- |
| 5 mm | +28 | +10 | 5.010 | 5.028 | 18 |
| 6 mm | +28 | +10 | 6.010 | 6.028 | 18 |
| 8 mm | +35 | +13 | 8.013 | 8.035 | 22 |
| 10 mm | +35 | +13 | 10.013 | 10.035 | 22 |
| 12 mm | +43 | +16 | 12.016 | 12.043 | 27 |
| 16 mm | +43 | +16 | 16.016 | 16.043 | 27 |
| 20 mm | +53 | +20 | 20.020 | 20.053 | 33 |
| 25 mm | +53 | +20 | 25.020 | 25.053 | 33 |
| 30 mm | +53 | +20 | 30.020 | 30.053 | 33 |
| 40 mm | +64 | +25 | 40.025 | 40.064 | 39 |
| 50 mm | +64 | +25 | 50.025 | 50.064 | 39 |
| 80 mm | +76 | +30 | 80.030 | 80.076 | 46 |
| 100 mm | +90 | +36 | 100.036 | 100.090 | 54 |

_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 F8

### F8 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 F8 Tolerance

### What is an F8 tolerance?

F8 is an ISO 286 hole tolerance: fundamental deviation F at IT grade IT8. Close running hole for shaft-basis fits with lubrication. Close running clearance describes what the F deviation does.

### What is the tolerance on a 25 mm F8 hole?

A 25 mm F8 hole runs 25.020 to 25.053 mm — deviations +20 to +53 µm, a tolerance band of 33 µm.

## Fits Built on F8

Standard hole/shaft pairs that use F8 as their hole.

| 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)

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*Source: [ShopMath](https://shopmath.org/fits/f8) — data verified August 1, 2026. Reference data; verify against the governing standard before manufacture.*