ISO 286 · shaft tolerance · IT9
d9 Tolerance — Shaft Limits by Nominal Size
https://shopmath.org/fits/d9 · data verified August 1, 2026
A 25 mm d9 shaft runs 24.883 to 24.935 mm — deviations of -117 to -65 µm on a tolerance band 52 µm wide. The d sets where the band sits (free running clearance) and IT9 sets how wide it is. Free running shaft where accuracy is not essential. All values apply at 20 °C.
- Feature
- shaft
- Letter
- d
- Grade
- IT9
- Sizes
- 13
- Standard
- ISO 286-1:2010
d9 shaft at Ø25 mm · deviation, µm
-65 / -117
- Max Ø
- 24.935mm
- Min Ø
- 24.883mm
- Band
- 52µm
Deviations from the 25 mm nominal size, at 20 °C. Every other verified size is in the table below.
- Source
- ISO 286-1:2010, ISO 286-2:2010
- Formula
- max Ø = nominal + es min Ø = nominal + ei
- Assumptions
- Ø25 mm nominal, 18–30 mm size step, plain cylindrical feature, 20 °C. Deviations are tabulated in the standard and compiled here; the limits are those deviations added to the nominal size.
- Verified
- August 1, 2026
d9 Shaft Limits at Every Verified Nominal Size
Deviations in micrometres and finished limits in millimetres. These are the thirteen nominal sizes with verified demand; the deviation pattern continues across the full ISO 286 size range.
| Property | Deviation, µm | Limits, mm | Property | ||
|---|---|---|---|---|---|
| Nominal Ø | Upper | Lower | Min | Max | Tolerance band, µm |
| 5 mm | -30 | -60 | 4.940 | 4.970 | 30 |
| 6 mm | -30 | -60 | 5.940 | 5.970 | 30 |
| 8 mm | -40 | -76 | 7.924 | 7.960 | 36 |
| 10 mm | -40 | -76 | 9.924 | 9.960 | 36 |
| 12 mm | -50 | -93 | 11.907 | 11.950 | 43 |
| 16 mm | -50 | -93 | 15.907 | 15.950 | 43 |
| 20 mm | -65 | -117 | 19.883 | 19.935 | 52 |
| 25 mm | -65 | -117 | 24.883 | 24.935 | 52 |
| 30 mm | -65 | -117 | 29.883 | 29.935 | 52 |
| 40 mm | -80 | -142 | 39.858 | 39.920 | 62 |
| 50 mm | -80 | -142 | 49.858 | 49.920 | 62 |
| 80 mm | -100 | -174 | 79.826 | 79.900 | 74 |
| 100 mm | -120 | -207 | 99.793 | 99.880 | 87 |
Deviations are relative to the nominal size: positive is above it, negative below. Limits assume the ISO 286 reference temperature of 20 °C.
The IT9 Tolerance Grade in d9, Across ISO 286 Size Bands
The number in d9 is the IT grade, and it sets how wide the tolerance band is. The band widens with size — that is the whole point of a graded tolerance system.
| Nominal size band | Tolerance, µm | Tolerance, mm |
|---|---|---|
| over 0 to 3 mm | 25 | 0.025 |
| over 3 to 6 mm | 30 | 0.030 |
| over 6 to 10 mm | 36 | 0.036 |
| over 10 to 18 mm | 43 | 0.043 |
| over 18 to 30 mm | 52 | 0.052 |
| over 30 to 50 mm | 62 | 0.062 |
| over 50 to 80 mm | 74 | 0.074 |
| over 80 to 120 mm | 87 | 0.087 |
| over 120 to 180 mm | 100 | 0.100 |
| over 180 to 250 mm | 115 | 0.115 |
| over 250 to 315 mm | 130 | 0.130 |
| over 315 to 400 mm | 140 | 0.140 |
| over 400 to 500 mm | 155 | 0.155 |
Bands are open at the bottom and closed at the top: 'over 18 to 30 mm' includes 30 mm and excludes 18 mm.
Fundamental Deviation of the d shaft Tolerance in d9
The letter in d9 sets where the tolerance band sits relative to the nominal size: free running clearance. The grade then adds the band width to that starting point.
| Nominal size band | Fundamental deviation, µm | Which limit it sets |
|---|---|---|
| over 0 to 3 mm | -20 | upper (es / ES) |
| over 3 to 6 mm | -30 | upper (es / ES) |
| over 6 to 10 mm | -40 | upper (es / ES) |
| over 10 to 14 mm | -50 | upper (es / ES) |
| over 14 to 18 mm | -50 | upper (es / ES) |
| over 18 to 24 mm | -65 | upper (es / ES) |
| over 24 to 30 mm | -65 | upper (es / ES) |
| over 30 to 40 mm | -80 | upper (es / ES) |
| over 40 to 50 mm | -80 | upper (es / ES) |
| over 50 to 65 mm | -100 | upper (es / ES) |
| over 65 to 80 mm | -100 | upper (es / ES) |
| over 80 to 100 mm | -120 | upper (es / ES) |
| over 100 to 120 mm | -120 | upper (es / ES) |
| over 120 to 140 mm | -145 | upper (es / ES) |
| over 140 to 160 mm | -145 | upper (es / ES) |
| over 160 to 180 mm | -145 | upper (es / ES) |
| over 180 to 200 mm | -170 | upper (es / ES) |
| over 200 to 225 mm | -170 | upper (es / ES) |
| over 225 to 250 mm | -170 | upper (es / ES) |
| over 250 to 280 mm | -190 | upper (es / ES) |
| over 280 to 315 mm | -190 | upper (es / ES) |
| over 315 to 355 mm | -210 | upper (es / ES) |
| over 355 to 400 mm | -210 | upper (es / ES) |
| over 400 to 450 mm | -230 | upper (es / ES) |
| over 450 to 500 mm | -230 | upper (es / ES) |
The fundamental deviation is the limit nearest the nominal size. For a hole it is the lower limit for letters A–H and the upper limit above that; the other limit follows from the IT grade.
Standard Fits That Use the d9 Tolerance
A tolerance on its own is half a fit. These are the standard ISO 286 pairs d9 appears in, with what each one is used for.
| Fit | Type | Basis | What it is for |
|---|---|---|---|
| H9/d9 | clearance | hole basis | Free running. Good where accuracy is not essential and clearance can be generous. |
Clearance, transition and interference are properties of the pair, not of either tolerance alone.
Sources and Method for the d9 Tolerance Data
- d9 limitscomputed
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
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.
- IT9 tolerance gradecompiled
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. Formula per ISO 286-1 standard tolerance factor and fundamental deviation formulas, used as a validation harness only per docs/research/data-sourcing.md §3.6
Compiled from independent public sources that agree cell-for-cell.
- d fundamental deviationcompiled
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
Compiled from independent public sources that agree cell-for-cell.
- Formula
Limits from the deviations, shaft tolerance
max Ø = nominal + es min Ø = nominal + ei es = upper deviation (µm) ei = lower deviation (µm)
The deviations are tabulated in ISO 286-2 and compiled here; the limits are those deviations added to the nominal size, which is why both columns are shown.
- Assumptions
- Values apply at the ISO 286 reference temperature of 20 °C.
- Limits are for a plain cylindrical feature. A tolerance letter says nothing about surface finish, form or roundness — those 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 d9 Tolerance Reference
Citation
ShopMath. "d9 Tolerance — Shaft Limits by Nominal Size." ShopMath, verified August 1, 2026, https://shopmath.org/fits/d9
BibTeX
@misc{shopmath-fits-d9,
title = {d9 Tolerance — Shaft Limits by Nominal Size},
author = {{ShopMath}},
year = {2026},
howpublished = {\url{https://shopmath.org/fits/d9}},
note = {Data verified 2026-08-01}
}Permanent URL
https://shopmath.org/fits/d9
Common Questions About the d9 Tolerance
What is the tolerance of a 25 mm d9 shaft?
- A 25 mm d9 shaft runs 24.883 to 24.935 mm — deviations of -117 to -65 µm, a tolerance band 52 µm wide.
What does d9 mean?
- d9 is an ISO 286 shaft tolerance. The d sets the fundamental deviation — free running clearance — and the 9 is the IT9 tolerance grade, which sets how wide the band is. Free running shaft where accuracy is not essential.
How wide is the IT9 tolerance band?
- IT9 is 52 µm wide for nominal sizes over 18 up to 30 mm, and widens with size — the full band table is on this page.
Which fits use d9?
- d9 appears in 1 standard ISO 286 fits: H9/d9 (clearance).
d9 at Ø25 mm · µm
-65 / -117
24.883 – 24.935 mm