What is the clearance of a 25 mm H7/n6 fit?

A 25 mm H7/n6 fit has -28 to +6 µm of clearance: the hole runs 25.000 to 25.021 mm and the shaft 25.015 to 25.028 mm. A negative figure is interference — the parts must be pressed, heated or chilled together.

What is H7/n6 used for?

Tight transition. Usually a press job. 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 H7/n6 fit change with size?

Across the 13 verified nominal sizes the clearance runs from -45 µm at 100 mm to +12 µm at 100 mm, because both tolerance bands widen with nominal size.

ISO 286 · transition fit · hole basis

H7/n6 Transition Fit — Hole and Shaft Limits by Size

https://shopmath.org/fits/h7-n6 · data verified August 1, 2026

A 25 mm H7/n6 fit gives -28 to +6 µm of clearance — a 25.000–25.021 mm hole on a 25.015–25.028 mm shaft. Tight transition. Usually a press job. Depending on where each part lands in tolerance, the joint may end up with a small clearance or a small interference. All values apply at 20 °C.

Type: transition
Hole: H7
Shaft: n6
Sizes: 13
Standard: ISO 286-1:2010

H7/n6 at Ø25 mm · clearance, µm

-28 … +6

Hole: 25.000–25.021mm
Shaft: 25.015–25.028mm

Negative is interference. At Ø25 mm this joint is 28 µm interference at worst case — an assembly force, not a slip fit.

H7/n6 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.

H7/n6 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	5.012	5.008	5.016	-16	+4	transition
6 mm	6.000	6.012	6.008	6.016	-16	+4	transition
8 mm	8.000	8.015	8.010	8.019	-19	+5	transition
10 mm	10.000	10.015	10.010	10.019	-19	+5	transition
12 mm	12.000	12.018	12.012	12.023	-23	+6	transition
16 mm	16.000	16.018	16.012	16.023	-23	+6	transition
20 mm	20.000	20.021	20.015	20.028	-28	+6	transition
25 mm	25.000	25.021	25.015	25.028	-28	+6	transition
30 mm	30.000	30.021	30.015	30.028	-28	+6	transition
40 mm	40.000	40.025	40.017	40.033	-33	+8	transition
50 mm	50.000	50.025	50.017	50.033	-33	+8	transition
80 mm	80.000	80.030	80.020	80.039	-39	+10	transition
100 mm	100.000	100.035	100.023	100.045	-45	+12	transition

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 H7/n6 Fit

H7/n6 is H7 on the hole and n6 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
H7 →
The default basic hole in hole-basis fitting — reamer and gauge sizes are built around it.
Shaft
n6 →
Tight transition shaft — usually needs a press for assembly.

Fits That Share a Tolerance With the H7/n6 Fit

Changing one half of the pair is how a design moves from clearance to interference. These fits keep H7 or n6 and change the other side.

ISO 286 fits sharing a hole or shaft tolerance with H7/n6
Fit	Type	What it is for
H7/g6	clearance	Sliding. Locates accurately, still moves and turns freely.
H7/h6	clearance	Locational clearance. Assembles by hand, no free movement intended.
H7/p6	interference	Locational interference. Rigid location in steel without the load capacity of a drive fit.
H7/r6	interference	Medium drive. The joint itself carries load.
H7/k6	transition	Locational transition. Accurate location, assembles with light force.
H7/m6	transition	Locational transition, tighter than k6.

Ordered loosest to tightest within each type.

Sources and Method for the H7/n6 Fit Data

H7/n6 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 H7/n6 Fit Reference

Citation

ShopMath. "H7/n6 Transition Fit — Hole and Shaft Limits by Size." ShopMath, verified August 1, 2026, https://shopmath.org/fits/h7-n6

BibTeX

@misc{shopmath-fits-h7-n6,
  title        = {H7/n6 Transition Fit — Hole and Shaft Limits by Size},
  author       = {{ShopMath}},
  year         = {2026},
  howpublished = {\url{https://shopmath.org/fits/h7-n6}},
  note         = {Data verified 2026-08-01}
}

Permanent URL

https://shopmath.org/fits/h7-n6

Common Questions About the H7/n6 Fit

What is the clearance of a 25 mm H7/n6 fit?: A 25 mm H7/n6 fit has -28 to +6 µm of clearance: the hole runs 25.000 to 25.021 mm and the shaft 25.015 to 25.028 mm. A negative figure is interference — the parts must be pressed, heated or chilled together.
Is H7/n6 a clearance, transition or interference fit?: H7/n6 is a transition fit. Depending on where each part lands in tolerance, the joint may end up with a small clearance or a small interference. Tight transition. Usually a press job.
What is H7/n6 used for?: Tight transition. Usually a press job. 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 H7/n6 fit change with size?: Across the 13 verified nominal sizes the clearance runs from -45 µm at 100 mm to +12 µm at 100 mm, because both tolerance bands widen with nominal size.

Every ISO 286 designation and fit · ISO 286 tolerance chart