General Tolerance Iso 2768-mk May 2026

| Nominal Size Range | Permissible Deviation (± mm) | |--------------------|-------------------------------| | 0.5 – 3 | ±0.2 | | >3 – 6 | ±0.5 |

If a specific dimension has a directly applied tolerance (e.g., 10±0.05), the general tolerance (±0.2 for 10 mm) is invalid for that feature. The individual tolerance takes precedence.

Applies to flatness, straightness, perpendicularity, symmetry, and circular runout.

| Nominal Size Range (mm) | Flatness / Straightness (mm) | Perpendicularity (mm) | Symmetry (mm) | Circular Runout (mm) | | :--- | :--- | :--- | :--- | :--- | | 0.5 to 10 | 0.05 | 0.1 | 0.5 | 0.1 | | >10 to 30 | 0.1 | 0.2 | 0.5 | 0.1 | | >30 to 100 | 0.1 | 0.3 | 0.5 | 0.1 | | >100 to 300 | 0.2 | 0.4 | 0.5 | 0.1 | | >300 to 1000 | 0.3 | 0.5 | 0.5 | 0.1 | | >1000 to 3000 | 0.4 | 0.6 | 0.5 | 0.1 | general tolerance iso 2768-mk

Important: For parallelism, the tolerance equals the value of the size tolerance. For positional tolerances, the standard recommends using ISO 2768-2 only for "non-functional" features; otherwise, individually specify.

The designation -mk specifies tolerance classes from both parts of the standard:

| Code | Refers to | Tolerance Class | Typical Application | |------|-----------|----------------|---------------------| | m | ISO 2768-1 (Linear/Angular) | Medium | General machining (lathe, mill, drilling) | | k | ISO 2768-2 (Geometrical) | Fine | Tighter form & position control | | Nominal Size Range | Permissible Deviation (±

Note: The first letter (m) is for linear/angular; the second letter (k) is for geometrical. Other common combos: -f (fine), -c (coarse), -v (very coarse).

This is where ISO 2768-mk becomes stricter than the 'f' (fine) class. Class 'k' tolerances are tighter than 'L' (coarse) but looser than 'H' (precision). The values depend on the nominal length of the feature.

| Range of Nominal Length (mm) | Straightness / Flatness (mm) | Perpendicularity (mm) | Symmetry (mm) | Runout (mm) | | --- | --- | --- | --- | --- | | 10 to 30 | 0.05 | 0.1 | 0.2 | 0.1 | | >30 to 100 | 0.1 | 0.2 | 0.3 | 0.2 | | >100 to 300 | 0.2 | 0.4 | 0.6 | 0.4 | | >300 to 1000 | 0.3 | 0.6 | 1.0 | 0.6 | | >1000 to 3000 | 0.4 | 0.8 | 1.5 | 0.8 | Important: For parallelism , the tolerance equals the

Interpretation: A 200 mm long milled surface under ISO 2768-mk must not warp by more than 0.2 mm (flatness). Its end face must be perpendicular to its base within 0.4 mm over the full length.

Angular tolerances are not constant; they depend on the length of the shorter side of the angle.

| Nominal Length of Shorter Side (mm) | Tolerance (mm per meter) | Tolerance (degrees/minutes) | | --- | --- | --- | | Up to 10 | ±1° | ±1° | | >10 to 50 | ±0°30' | ±0°30' | | >50 to 120 | ±0°20' | ±0°20' | | >120 to 400 | ±0°10' | ±0°10' | | >400 | ±0°5' | ±0°5' |

ISO 2768 is divided into two parts. When a drawing is marked with "ISO 2768-mK", it implies compliance with both parts:

The purpose of general tolerances is to define the permissible deviation for dimensions that are not individually indicated on the drawing. These tolerances represent the normal manufacturing accuracy achievable by standard workshop machinery.