ISO 286 · clearance fit · hole basis
H8/f7 Clearance Fit — Hole and Shaft Limits by Size
https://shopmath.org/fits/h8-f7 · data verified August 1, 2026
A 25 mm H8/f7 fit gives +20 to +74 µm of clearance — a 25.000–25.033 mm hole on a 24.959–24.980 mm shaft. Close running. The general-purpose lubricated journal fit. The hole is always larger than the shaft — the parts always assemble with a gap. All values apply at 20 °C.
- Type
- clearance
- Hole
- H8
- Shaft
- f7
- Sizes
- 13
- Standard
- ISO 286-1:2010
H8/f7 at Ø25 mm · clearance, µm
+20 … +74
- Hole
- 25.000–25.033mm
- Shaft
- 24.959–24.980mm
Clearance at Ø25 mm, at 20 °C. Every other verified size is in the table below.
H8/f7 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.
| Property | Hole, mm | Shaft, mm | Clearance, µm | Property | |||
|---|---|---|---|---|---|---|---|
| Nominal Ø | Min | Max | Min | Max | Min | Max | At this size |
| 5 mm | 5.000 | 5.018 | 4.978 | 4.990 | +10 | +40 | clearance |
| 6 mm | 6.000 | 6.018 | 5.978 | 5.990 | +10 | +40 | clearance |
| 8 mm | 8.000 | 8.022 | 7.972 | 7.987 | +13 | +50 | clearance |
| 10 mm | 10.000 | 10.022 | 9.972 | 9.987 | +13 | +50 | clearance |
| 12 mm | 12.000 | 12.027 | 11.966 | 11.984 | +16 | +61 | clearance |
| 16 mm | 16.000 | 16.027 | 15.966 | 15.984 | +16 | +61 | clearance |
| 20 mm | 20.000 | 20.033 | 19.959 | 19.980 | +20 | +74 | clearance |
| 25 mm | 25.000 | 25.033 | 24.959 | 24.980 | +20 | +74 | clearance |
| 30 mm | 30.000 | 30.033 | 29.959 | 29.980 | +20 | +74 | clearance |
| 40 mm | 40.000 | 40.039 | 39.950 | 39.975 | +25 | +89 | clearance |
| 50 mm | 50.000 | 50.039 | 49.950 | 49.975 | +25 | +89 | clearance |
| 80 mm | 80.000 | 80.046 | 79.940 | 79.970 | +30 | +106 | clearance |
| 100 mm | 100.000 | 100.054 | 99.929 | 99.964 | +36 | +125 | 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 H8/f7 Fit
H8/f7 is H8 on the hole and f7 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.
Sources and Method for the H8/f7 Fit Data
- H8/f7 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 to Cite This H8/f7 Fit Reference
Citation
ShopMath. "H8/f7 Clearance Fit — Hole and Shaft Limits by Size." ShopMath, verified August 1, 2026, https://shopmath.org/fits/h8-f7
BibTeX
@misc{shopmath-fits-h8-f7,
title = {H8/f7 Clearance Fit — Hole and Shaft Limits by Size},
author = {{ShopMath}},
year = {2026},
howpublished = {\url{https://shopmath.org/fits/h8-f7}},
note = {Data verified 2026-08-01}
}Permanent URL
https://shopmath.org/fits/h8-f7
Common Questions About the H8/f7 Fit
What is the clearance of a 25 mm H8/f7 fit?
- A 25 mm H8/f7 fit has +20 to +74 µm of clearance: the hole runs 25.000 to 25.033 mm and the shaft 24.959 to 24.980 mm.
Is H8/f7 a clearance, transition or interference fit?
- H8/f7 is a clearance fit. The hole is always larger than the shaft — the parts always assemble with a gap. Close running. The general-purpose lubricated journal fit.
What is H8/f7 used for?
- Close running. The general-purpose lubricated journal fit. 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 H8/f7 fit change with size?
- Across the 13 verified nominal sizes the clearance runs from +10 µm at 5 mm to +125 µm at 100 mm, because both tolerance bands widen with nominal size.