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ISO 286 REFERENCE TABLE · HOLE

H8 tolerance chart: ISO 286 hole limits by size

Static H8 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 H8 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

H8 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.
H8 ISO 286 hole deviations and limits for 13 nominal-size bands
Size band (mm)Representative nominal (mm)Upper deviation (µm)Lower deviation (µm)IT8 width (µm)Minimum / maximum (mm)
[1, 3]3+140143.000 / 3.014
(3, 6]6+180186.000 / 6.018
(6, 10]10+2202210.000 / 10.022
(10, 18]18+2702718.000 / 18.027
(18, 30]30+3303330.000 / 30.033
(30, 50]50+3903950.000 / 50.039
(50, 80]80+4604680.000 / 80.046
(80, 120]120+54054120.000 / 120.054
(120, 180]180+63063180.000 / 180.063
(180, 250]250+72072250.000 / 250.072
(250, 315]315+81081315.000 / 315.081
(315, 400]400+89089400.000 / 400.089
(400, 500]500+97097500.000 / 500.097

The IT8 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 H8 callouts

H8 keeps the H-hole lower deviation at zero while allowing a wider IT band than H7. Examples you can check across different size bands include:
25 MM WORKED CALLOUT25 H8 → 25.000 / 25.033 mm
Upper deviation
+33 µm
Lower deviation
0 µm
IT8 width
33 µm
Load this hole state in the calculator

READ THE CLASS CORRECTLY

H8: hole zone H, IT grade 8

H

Hole tolerance zone

Uppercase letters identify hole tolerance zones.

8

IT tolerance grade

The grade selects the published tolerance width for each nominal-size band.

µm → mm

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.

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