---
type: "fit-size"
designation: "H7"
nominal_size_mm: 30
feature: "hole"
letter: "H"
it_grade: "ITIT7"
upper_deviation_um: 21
lower_deviation_um: 0
min_dia_mm: 30
max_dia_mm: 30.021
it_tolerance_um: 21
standard: "ISO 286-1:2010, ISO 286-2:2010"
verified: "August 1, 2026"
url: https://shopmath.org/fits/h7/30mm
---

# 30 mm H7 Tolerance — Limits, Deviations and Band

A 30 mm H7 hole runs 30.000 to 30.021 mm — deviations +0 to +21 µm from nominal, on an ITIT7 band of 21 µm. The default basic hole in hole-basis fitting — reamer and gauge sizes are built around it.

- **Designation**: H7 at 30 mm
- **Feature**: hole
- **Upper limit**: 30.021 mm (+21 µm)
- **Lower limit**: 30.000 mm (+0 µm)
- **Tolerance band**: 21 µm (ITIT7)
- **Fundamental deviation**: H — Zero deviation — the basic hole
- **Standard**: ISO 286-1:2010, ISO 286-2:2010

## 30 mm H7 Limits

| Property | Micrometres | Millimetres |
| --- | --- | --- |
| Upper deviation | +21 | 0.021 |
| Lower deviation | +0 | 0.000 |
| Tolerance band (IT) | 21 | 0.021 |
| Maximum diameter |  | 30.021 |
| Minimum diameter |  | 30.000 |

_Deviations are measured from the nominal size. A diameter outside the two limits is a reject._

## Other Standard Tolerances at 30 mm

The other ISO 286 designations that carry a page at 30 mm — the comparison to make when H7 is the wrong fit.

| Designation | Feature | Lower deviation (µm) | Upper deviation (µm) | Min Ø (mm) | Max Ø (mm) | IT band (µm) |
| --- | --- | --- | --- | --- | --- | --- |
| [f7](https://shopmath.org/fits/f7/30mm.md) | shaft | -41 | -20 | 29.959 | 29.980 | 21 |
| [g6](https://shopmath.org/fits/g6/30mm.md) | shaft | -20 | -7 | 29.980 | 29.993 | 13 |
| [h6](https://shopmath.org/fits/h6/30mm.md) | shaft | -13 | +0 | 29.987 | 30.000 | 13 |
| [h7](https://shopmath.org/fits/h7-shaft/30mm.md) | shaft | -21 | +0 | 29.979 | 30.000 | 21 |
| [p6](https://shopmath.org/fits/p6/30mm.md) | shaft | +22 | +35 | 30.022 | 30.035 | 13 |

## ISO 286 Standard Tolerance Grades at 30 mm

Every IT grade in the size band 30 mm falls in. The letter sets where the band sits; the IT grade sets how wide it is.

| Grade | Tolerance (µm) | Tolerance (mm) |
| --- | --- | --- |
| IT5 | 9 | 0.009 |
| IT6 | 13 | 0.013 |
| IT7 | 21 | 0.021 |
| IT8 | 33 | 0.033 |
| IT9 | 52 | 0.052 |
| IT10 | 84 | 0.084 |
| IT11 | 130 | 0.130 |
| IT12 | 210 | 0.210 |

## Sources and Method for 30 mm H7

### H7 at 30 mm

- **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.
- ISO 286 tabulates per size band, so this value holds across the band the nominal size falls in.
- 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 30 mm H7

### What is the tolerance for a 30 mm H7 hole?

A 30 mm H7 hole is 30.000 to 30.021 mm — deviations +0 to +21 µm from nominal, a total tolerance band of 21 µm.

### What size reamer or bore does a 30 mm H7 hole need?

Aim for the middle of the band: 30.011 mm, with 21 µm of total spread available between 30.000 and 30.021 mm.

### How much is 21 µm in millimetres and inches?

21 µm is 0.021 mm, or 0.00083 in.

## Related pages

- Smaller size: [25 mm H7](https://shopmath.org/fits/h7/25mm.md)
- Larger size: [40 mm H7](https://shopmath.org/fits/h7/40mm.md)
- All sizes of this tolerance: [H7 limits by size](https://shopmath.org/fits/h7.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/h7/30mm) — data verified August 1, 2026. Reference data; verify against the governing standard before manufacture.*