400 — 1000: ±0.8
Avoids unneeded "fine" tolerances that increase machining time and tooling cost.
The "MH" in ISO 2768-MH refers to the specific tolerance class, which is defined as "medium" tolerance. This class provides a balance between the precision required for a part or component and the practical limitations of manufacturing processes.
In practice, for most machined parts under 120 mm, you get ±1 degree. iso 2768-mh tolerance chart
It ensures consistency across different suppliers, machines, and manufacturing floors globally.
Geometrical tolerances restrict the form variation of a surface or line over its total length. Nominal Length Range (mm) General Tolerance (Class H) Over 10 to 30 Over 30 to 100 Over 100 to 300 Over 300 to 1000 Over 1000 to 3000 5. Perpendicularity (ISO 2768-2, Class H)
This international standard simplifies technical drawings by providing "general tolerances." If a specific tolerance isn't noted next to a dimension, the workshop refers to this chart to understand the allowable margin of error. 400 — 1000: ±0
For linear dimensions (lengths, widths, depths, steps, etc.), class applies.
Limitations:
Because ISO is a globally recognized standard, a drawing created in the United States or Europe can be sent to a machine shop anywhere in the world and interpreted exactly the same way. When Not to Use ISO 2768-mh In practice, for most machined parts under 120
The designation is split into two parts, representing different tolerance classes:
In mechanical engineering and manufacturing, specifying precise tolerances for every single dimension on a technical drawing is time-consuming and often unnecessary. To streamline this process, the was created to provide "general tolerances"—default, acceptable variations for features that don’t require individual tolerance callouts.
Below is a practical reproduction of the ISO 2768‑1 linear tolerance values for grade "m" (medium). Note: the exact numbers below are representative; always verify against the official ISO 2768‑1:1989/2000 standard edition used by your organization or the most current national adoption.
The designation "ISO 2768-mh" combines two distinct parts of the ISO 2768 standard to define allowable variations for a part.
General geometrical tolerances specified by ISO 2768-2 for the "H" (fine) class. All values are in mm.