What is the clearance of a 25 mm N7/h6 fit?

A 25 mm N7/h6 fit has -28 to +6 µm of clearance: the hole runs 24.972 to 24.993 mm and the shaft 24.987 to 25.000 mm. A negative figure is interference — the parts must be pressed, heated or chilled together.

What is N7/h6 used for?

Tight transition, shaft basis. It is a shaft-basis fit, so the shaft is held to one standard tolerance and the hole is machined to suit.

How does the N7/h6 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 · shaft basis

N7/h6 Transition Fit — Hole and Shaft Limits by Size

https://shopmath.org/fits/n7-h6 · data verified August 1, 2026

A 25 mm N7/h6 fit gives -28 to +6 µm of clearance — a 24.972–24.993 mm hole on a 24.987–25.000 mm shaft. Tight transition, shaft basis. 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: N7
Shaft: h6
Sizes: 13
Standard: ISO 286-1:2010

N7/h6 at Ø25 mm · clearance, µm

-28 … +6

Hole: 24.972–24.993mm
Shaft: 24.987–25.000mm

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

N7/h6 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.

N7/h6 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	4.984	4.996	4.992	5.000	-16	+4	transition
6 mm	5.984	5.996	5.992	6.000	-16	+4	transition
8 mm	7.981	7.996	7.991	8.000	-19	+5	transition
10 mm	9.981	9.996	9.991	10.000	-19	+5	transition
12 mm	11.977	11.995	11.989	12.000	-23	+6	transition
16 mm	15.977	15.995	15.989	16.000	-23	+6	transition
20 mm	19.972	19.993	19.987	20.000	-28	+6	transition
25 mm	24.972	24.993	24.987	25.000	-28	+6	transition
30 mm	29.972	29.993	29.987	30.000	-28	+6	transition
40 mm	39.967	39.992	39.984	40.000	-33	+8	transition
50 mm	49.967	49.992	49.984	50.000	-33	+8	transition
80 mm	79.961	79.991	79.981	80.000	-39	+10	transition
100 mm	99.955	99.990	99.978	100.000	-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 N7/h6 Fit

N7/h6 is N7 on the hole and h6 on the shaft. It is a shaft-basis fit: the shaft is held to one standard tolerance and the hole is varied — which is what you want when the shaft is a drawn or ground bar bought to size.

Hole
N7 →
Shaft-basis transition hole biased toward interference.
Shaft
h6 →
Precision basic shaft — zero upper deviation, the reference for locational clearance fits.

Fits That Share a Tolerance With the N7/h6 Fit

Changing one half of the pair is how a design moves from clearance to interference. These fits keep N7 or h6 and change the other side.

ISO 286 fits sharing a hole or shaft tolerance with N7/h6
Fit	Type	What it is for
G7/h6	clearance	Sliding, shaft basis. The h6 shaft is the reference and the hole carries the clearance.
H7/h6	clearance	Locational clearance. Assembles by hand, no free movement intended.
P7/h6	interference	Locational interference, shaft basis.
K7/h6	transition	Locational transition, shaft basis.

Ordered loosest to tightest within each type.

Sources and Method for the N7/h6 Fit Data

N7/h6 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 N7/h6 Fit Reference

Citation

ShopMath. "N7/h6 Transition Fit — Hole and Shaft Limits by Size." ShopMath, verified August 1, 2026, https://shopmath.org/fits/n7-h6

BibTeX

@misc{shopmath-fits-n7-h6,
  title        = {N7/h6 Transition Fit — Hole and Shaft Limits by Size},
  author       = {{ShopMath}},
  year         = {2026},
  howpublished = {\url{https://shopmath.org/fits/n7-h6}},
  note         = {Data verified 2026-08-01}
}

Permanent URL

https://shopmath.org/fits/n7-h6

Common Questions About the N7/h6 Fit

What is the clearance of a 25 mm N7/h6 fit?: A 25 mm N7/h6 fit has -28 to +6 µm of clearance: the hole runs 24.972 to 24.993 mm and the shaft 24.987 to 25.000 mm. A negative figure is interference — the parts must be pressed, heated or chilled together.
Is N7/h6 a clearance, transition or interference fit?: N7/h6 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, shaft basis.
What is N7/h6 used for?: Tight transition, shaft basis. It is a shaft-basis fit, so the shaft is held to one standard tolerance and the hole is machined to suit.
How does the N7/h6 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