Hole tolerance zone
Uppercase letters identify hole tolerance zones.
ISO 286 REFERENCE TABLE · HOLE
H7 tolerance chart: ISO 286 hole limits by size
Static H7 deviations and hole limits at the upper-bound nominal of every ISO 286 size band from 1 to 500 mm.This page answers a class-specific H7 tolerance chart query. The ISO 286 fits calculator remains the tool for arbitrary nominal sizes, paired hole/shaft callouts, measured values, and shareable calculations.
13 ISO 286 SIZE BANDS
H7 hole limits by representative nominal size
Each representative nominal is the upper boundary of its displayed size band. Deviations and IT width are shown in micrometres; the resulting minimum and maximum are shown in millimetres.| Size band (mm) | Representative nominal (mm) | Upper deviation (µm) | Lower deviation (µm) | IT7 width (µm) | Minimum / maximum (mm) |
|---|---|---|---|---|---|
| [1, 3] | 3 | +10 | 0 | 10 | 3.000 / 3.010 |
| (3, 6] | 6 | +12 | 0 | 12 | 6.000 / 6.012 |
| (6, 10] | 10 | +15 | 0 | 15 | 10.000 / 10.015 |
| (10, 18] | 18 | +18 | 0 | 18 | 18.000 / 18.018 |
| (18, 30] | 30 | +21 | 0 | 21 | 30.000 / 30.021 |
| (30, 50] | 50 | +25 | 0 | 25 | 50.000 / 50.025 |
| (50, 80] | 80 | +30 | 0 | 30 | 80.000 / 80.030 |
| (80, 120] | 120 | +35 | 0 | 35 | 120.000 / 120.035 |
| (120, 180] | 180 | +40 | 0 | 40 | 180.000 / 180.040 |
| (180, 250] | 250 | +46 | 0 | 46 | 250.000 / 250.046 |
| (250, 315] | 315 | +52 | 0 | 52 | 315.000 / 315.052 |
| (315, 400] | 400 | +57 | 0 | 57 | 400.000 / 400.057 |
| (400, 500] | 500 | +63 | 0 | 63 | 500.000 / 500.063 |
The IT7 tolerance width is constant within each displayed size band. Values shown are calculated at the representative upper-bound nominal. Some letter zones use finer fundamental-deviation sub-bands, so deviations may vary within a displayed band; use the calculator for the exact nominal.
Within a band where the deviations are unchanged, the micrometre deviations stay fixed while the absolute millimetre limits move with the selected nominal size.
DRAWING EXAMPLES
Common H7 callouts
H7 is a hole-basis class used with different shaft zones to create close-running, transition, and press-fit selections. Examples you can check across different size bands include:25 MM WORKED CALLOUT25 H7 → 25.000 / 25.021 mm
- Upper deviation
- +21 µm
- Lower deviation
- 0 µm
- IT7 width
- 21 µm
READ THE CLASS CORRECTLY
H7: hole zone H, IT grade 7
IT tolerance grade
The grade selects the published tolerance width for each nominal-size band.
Deviation to absolute limit
Each deviation is added to the exact nominal diameter after conversion from micrometres to millimetres.
This static table is an engineering reference, not a replacement for a controlled drawing or licensed ISO 286 standard. Confirm standard edition, feature function, geometry, surface finish, and inspection method.
Return to the ISO 286 fits & tolerance calculator