ISO 286 · shaft tolerance · IT7
f7 Tolerance — Shaft Limits by Nominal Size
https://shopmath.org/fits/f7 · data verified August 1, 2026
A 25 mm f7 shaft runs 24.959 to 24.980 mm — deviations of -41 to -20 µm on a tolerance band 21 µm wide. The f sets where the band sits (close running clearance) and IT7 sets how wide it is. Close running shaft — the standard choice for lubricated journals at moderate speed. All values apply at 20 °C.
- Feature
- shaft
- Letter
- f
- Grade
- IT7
- Sizes
- 13
- Standard
- ISO 286-1:2010
f7 shaft at Ø25 mm · deviation, µm
-20 / -41
- Max Ø
- 24.980mm
- Min Ø
- 24.959mm
- Band
- 21µm
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
f7 Shaft Limits at Every Verified Nominal Size
Deviations in micrometres and finished limits in millimetres. Every size links to its own page.
| Property | Deviation, µm | Limits, mm | Property | ||
|---|---|---|---|---|---|
| Nominal Ø | Upper | Lower | Min | Max | Tolerance band, µm |
| 5 mm | -10 | -22 | 4.978 | 4.990 | 12 |
| 6 mm | -10 | -22 | 5.978 | 5.990 | 12 |
| 8 mm | -13 | -28 | 7.972 | 7.987 | 15 |
| 10 mm | -13 | -28 | 9.972 | 9.987 | 15 |
| 12 mm | -16 | -34 | 11.966 | 11.984 | 18 |
| 16 mm | -16 | -34 | 15.966 | 15.984 | 18 |
| 20 mm | -20 | -41 | 19.959 | 19.980 | 21 |
| 25 mm | -20 | -41 | 24.959 | 24.980 | 21 |
| 30 mm | -20 | -41 | 29.959 | 29.980 | 21 |
| 40 mm | -25 | -50 | 39.950 | 39.975 | 25 |
| 50 mm | -25 | -50 | 49.950 | 49.975 | 25 |
| 80 mm | -30 | -60 | 79.940 | 79.970 | 30 |
| 100 mm | -36 | -71 | 99.929 | 99.964 | 35 |
Deviations are relative to the nominal size: positive is above it, negative below. Limits assume the ISO 286 reference temperature of 20 °C.
The IT7 Tolerance Grade in f7, Across ISO 286 Size Bands
The number in f7 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 | 10 | 0.010 |
| over 3 to 6 mm | 12 | 0.012 |
| over 6 to 10 mm | 15 | 0.015 |
| over 10 to 18 mm | 18 | 0.018 |
| over 18 to 30 mm | 21 | 0.021 |
| over 30 to 50 mm | 25 | 0.025 |
| over 50 to 80 mm | 30 | 0.030 |
| over 80 to 120 mm | 35 | 0.035 |
| over 120 to 180 mm | 40 | 0.040 |
| over 180 to 250 mm | 46 | 0.046 |
| over 250 to 315 mm | 52 | 0.052 |
| over 315 to 400 mm | 57 | 0.057 |
| over 400 to 500 mm | 63 | 0.063 |
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 f shaft Tolerance in f7
The letter in f7 sets where the tolerance band sits relative to the nominal size: close 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 | -6 | upper (es / ES) |
| over 3 to 6 mm | -10 | upper (es / ES) |
| over 6 to 10 mm | -13 | upper (es / ES) |
| over 10 to 14 mm | -16 | upper (es / ES) |
| over 14 to 18 mm | -16 | upper (es / ES) |
| over 18 to 24 mm | -20 | upper (es / ES) |
| over 24 to 30 mm | -20 | upper (es / ES) |
| over 30 to 40 mm | -25 | upper (es / ES) |
| over 40 to 50 mm | -25 | upper (es / ES) |
| over 50 to 65 mm | -30 | upper (es / ES) |
| over 65 to 80 mm | -30 | upper (es / ES) |
| over 80 to 100 mm | -36 | upper (es / ES) |
| over 100 to 120 mm | -36 | upper (es / ES) |
| over 120 to 140 mm | -43 | upper (es / ES) |
| over 140 to 160 mm | -43 | upper (es / ES) |
| over 160 to 180 mm | -43 | upper (es / ES) |
| over 180 to 200 mm | -50 | upper (es / ES) |
| over 200 to 225 mm | -50 | upper (es / ES) |
| over 225 to 250 mm | -50 | upper (es / ES) |
| over 250 to 280 mm | -56 | upper (es / ES) |
| over 280 to 315 mm | -56 | upper (es / ES) |
| over 315 to 355 mm | -62 | upper (es / ES) |
| over 355 to 400 mm | -62 | upper (es / ES) |
| over 400 to 450 mm | -68 | upper (es / ES) |
| over 450 to 500 mm | -68 | 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 f7 Tolerance
A tolerance on its own is half a fit. These are the standard ISO 286 pairs f7 appears in, with what each one is used for.
| Fit | Type | Basis | What it is for |
|---|---|---|---|
| H8/f7 | clearance | hole basis | Close running. The general-purpose lubricated journal fit. |
Clearance, transition and interference are properties of the pair, not of either tolerance alone.
Sources and Method for the f7 Tolerance Data
- f7 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.
- IT7 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.
- f 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 f7 Tolerance Reference
Citation
ShopMath. "f7 Tolerance — Shaft Limits by Nominal Size." ShopMath, verified August 1, 2026, https://shopmath.org/fits/f7
BibTeX
@misc{shopmath-fits-f7,
title = {f7 Tolerance — Shaft Limits by Nominal Size},
author = {{ShopMath}},
year = {2026},
howpublished = {\url{https://shopmath.org/fits/f7}},
note = {Data verified 2026-08-01}
}Permanent URL
https://shopmath.org/fits/f7
Common Questions About the f7 Tolerance
What is the tolerance of a 25 mm f7 shaft?
- A 25 mm f7 shaft runs 24.959 to 24.980 mm — deviations of -41 to -20 µm, a tolerance band 21 µm wide.
What does f7 mean?
- f7 is an ISO 286 shaft tolerance. The f sets the fundamental deviation — close running clearance — and the 7 is the IT7 tolerance grade, which sets how wide the band is. Close running shaft — the standard choice for lubricated journals at moderate speed.
How wide is the IT7 tolerance band?
- IT7 is 21 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 f7?
- f7 appears in 1 standard ISO 286 fits: H8/f7 (clearance).
Is there a f7 page for each nominal size?
- Yes — f7 carries a page for each of the thirteen nominal sizes with verified demand, from 5 mm to 100 mm, each with the limits, the IT grades at that size and the fits available there.
f7 at Ø25 mm · µm
-20 / -41
24.959 – 24.980 mm