What is the clearance of a 25 mm H9/d9 fit?

A 25 mm H9/d9 fit has +65 to +169 µm of clearance: the hole runs 25.000 to 25.052 mm and the shaft 24.883 to 24.935 mm.

Is H9/d9 a clearance, transition or interference fit?

H9/d9 is a clearance fit. The hole is always larger than the shaft — the parts always assemble with a gap. Free running. Good where accuracy is not essential and clearance can be generous.

What is H9/d9 used for?

Free running. Good where accuracy is not essential and clearance can be generous. It is a hole-basis fit, so the hole is held to one standard tolerance and the shaft is machined to suit.

How does the H9/d9 fit change with size?

Across the 13 verified nominal sizes the clearance runs from +30 µm at 5 mm to +294 µm at 100 mm, because both tolerance bands widen with nominal size.

ISO 286 · clearance fit · hole basis

H9/d9 Clearance Fit — Hole and Shaft Limits by Size

https://shopmath.org/fits/h9-d9 · data verified August 1, 2026

A 25 mm H9/d9 fit gives +65 to +169 µm of clearance — a 25.000–25.052 mm hole on a 24.883–24.935 mm shaft. Free running. Good where accuracy is not essential and clearance can be generous. The hole is always larger than the shaft — the parts always assemble with a gap. All values apply at 20 °C.

Type: clearance
Hole: H9
Shaft: d9
Sizes: 13
Standard: ISO 286-1:2010

H9/d9 at Ø25 mm · clearance, µm

+65 … +169

Hole: 25.000–25.052mm
Shaft: 24.883–24.935mm

Clearance at Ø25 mm, at 20 °C. Every other verified size is in the table below.

H9/d9 Fit — Hole and Shaft Limits with Clearance, by Nominal Size

Both parts' limits in millimetres and the resulting clearance in micrometres. Negative clearance is interference: the shaft is larger than the hole and the joint needs force, heat or cold to assemble.

H9/d9 fit — hole limits, shaft limits and clearance by nominal size
Property	Hole, mm		Shaft, mm		Clearance, µm		Property
Nominal Ø	Min	Max	Min	Max	Min	Max	At this size
5 mm	5.000	5.030	4.940	4.970	+30	+90	clearance
6 mm	6.000	6.030	5.940	5.970	+30	+90	clearance
8 mm	8.000	8.036	7.924	7.960	+40	+112	clearance
10 mm	10.000	10.036	9.924	9.960	+40	+112	clearance
12 mm	12.000	12.043	11.907	11.950	+50	+136	clearance
16 mm	16.000	16.043	15.907	15.950	+50	+136	clearance
20 mm	20.000	20.052	19.883	19.935	+65	+169	clearance
25 mm	25.000	25.052	24.883	24.935	+65	+169	clearance
30 mm	30.000	30.052	29.883	29.935	+65	+169	clearance
40 mm	40.000	40.062	39.858	39.920	+80	+204	clearance
50 mm	50.000	50.062	49.858	49.920	+80	+204	clearance
80 mm	80.000	80.074	79.826	79.900	+100	+248	clearance
100 mm	100.000	100.087	99.793	99.880	+120	+294	clearance

Minimum clearance is the largest shaft in the smallest hole; maximum clearance is the smallest shaft in the largest hole. Values apply at the ISO 286 reference temperature of 20 °C.

The Hole and Shaft Tolerances That Make the H9/d9 Fit

H9/d9 is H9 on the hole and d9 on the shaft. It is a hole-basis fit: the hole is held to one standard tolerance and the shaft is varied to change the fit — which is what you want when the hole is reamed or bored to a standard size.

Hole
H9 →
Basic hole for free running fits with generous clearance.
Shaft
d9 →
Free running shaft where accuracy is not essential.

Sources and Method for the H9/d9 Fit Data

H9/d9 limitscomputed

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

Verified against parkergreene/isofits ISO 286-2 limit tables (MIT); ISO 286-1 formula harness — 2067 checks passed

Computed from the standard's formulas, then checked against published tables.

Formula

Clearance from the two tolerance bands

max clearance  =  hole max − shaft min
min clearance  =  hole min − shaft max

A negative result is interference. Both are computed from the compiled ISO 286-2 deviations, not from the ISO 286-1 formula, which deviates from the published table by up to 13%.

Assumptions

Values apply at the ISO 286 reference temperature of 20 °C. A joint assembled hot or cold, or running hot, is not at these limits.
The tolerances cover size only. Form, roundness, cylindricity and surface finish all affect how a fit behaves and need their own callouts.
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

How this data is built and checked →

How to Cite This H9/d9 Fit Reference

Citation

ShopMath. "H9/d9 Clearance Fit — Hole and Shaft Limits by Size." ShopMath, verified August 1, 2026, https://shopmath.org/fits/h9-d9

BibTeX

@misc{shopmath-fits-h9-d9,
  title        = {H9/d9 Clearance Fit — Hole and Shaft Limits by Size},
  author       = {{ShopMath}},
  year         = {2026},
  howpublished = {\url{https://shopmath.org/fits/h9-d9}},
  note         = {Data verified 2026-08-01}
}

Permanent URL

https://shopmath.org/fits/h9-d9

Common Questions About the H9/d9 Fit

What is the clearance of a 25 mm H9/d9 fit?: A 25 mm H9/d9 fit has +65 to +169 µm of clearance: the hole runs 25.000 to 25.052 mm and the shaft 24.883 to 24.935 mm.
Is H9/d9 a clearance, transition or interference fit?: H9/d9 is a clearance fit. The hole is always larger than the shaft — the parts always assemble with a gap. Free running. Good where accuracy is not essential and clearance can be generous.
What is H9/d9 used for?: Free running. Good where accuracy is not essential and clearance can be generous. It is a hole-basis fit, so the hole is held to one standard tolerance and the shaft is machined to suit.
How does the H9/d9 fit change with size?: Across the 13 verified nominal sizes the clearance runs from +30 µm at 5 mm to +294 µm at 100 mm, because both tolerance bands widen with nominal size.

Every ISO 286 designation and fit · ISO 286 tolerance chart