Iso 2768-mh Tolerance Chart ❲EXCLUSIVE • 2025❳

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.

Tolerance (grade m) for length L (mm):

(Explanation: For a nominal dimension within each size range, the permissible deviation is ± the listed value.)

Angular tolerances (when not otherwise specified), typical values for grade m:

Notes:

Why would an engineer specify "mh" instead of a tighter "ff" (fine/fine) or a looser "cL" (coarse/coarse)?

These are more restrictive than the 'm' class for form and orientation. The standard covers straightness, flatness, parallelism, perpendicularity, symmetry, and runout. Circularity and cylindricity are also included but often derived from the diameter tolerance.

| Nominal Length Range (mm) | Tolerance Class 'h' (mm) | | :--- | :--- | | up to 10 | 0.02 | | >10 up to 30 | 0.05 | | >30 up to 100 | 0.1 | | >100 up to 300 | 0.2 | | >300 up to 1000 | 0.5 | | >1000 up to 3000 | 1.0 |

Interpretation: A 200 mm long surface must be flat within 0.2 mm. A hole's axis must be perpendicular to a reference surface within a 0.1 mm cylindrical zone if the feature size is between 30-100 mm. iso 2768-mh tolerance chart

If you work in mechanical design or manufacturing, you’ve likely seen the notation "ISO 2768-mH" on a drawing title block.

But what does it actually tell the machinist or the inspector? It is shorthand for a "Medium" level of accuracy on linear dimensions and a "Coarse" level for geometrical tolerances.

Here is a quick breakdown of what the chart tells us and why it matters for your parts.

Tolerances in mm for nominal size ranges. Applies to external radii, chamfers, and linear dimensions (except broken edges). Below is a practical reproduction of the ISO

| Nominal Size Range (mm) | Tolerance (mm) | |------------------------|----------------| | 0.5 up to 3 | ±0.1 | | >3 up to 6 | ±0.1 | | >6 up to 30 | ±0.2 | | >30 up to 120 | ±0.3 | | >120 up to 400 | ±0.5 | | >400 up to 1000 | ±0.8 | | >1000 up to 2000 | ±1.2 | | >2000 up to 4000 | ±2.0 |

Applies to dimensions where no individual tolerance is specified.

| Nominal Length Range (mm) | Tolerance (mm) | |--------------------------|----------------| | ≤ 10 | 0.02 | | >10 to 30 | 0.05 | | >30 to 100 | 0.1 | | >100 to 300 | 0.2 | | >300 to 1000 | 0.3 | | >1000 to 3000 | 0.4 |