Iso 2768-mh Tolerance Chart May 2026

The 'm' stands for Medium accuracy. This is the most common standard for general machining. It applies to linear dimensions (lengths, widths, heights) unless a specific tolerance is called out directly on the dimension.

The Chart at a Glance (ISO 2768-m):

| Nominal Dimension (mm) | Permissible Deviation (mm) | | :--- | :--- | | 0.5 up to 3 | ±0.1 | | Over 3 up to 6 | ±0.1 | | Over 6 up to 30 | ±0.2 | | Over 30 up to 120 | ±0.3 | | Over 120 up to 400 | ±0.5 | | Over 400 up to 1000 | ±0.8 |

Note: For dimensions below 0.5mm, the deviation is generally specified directly on the drawing. iso 2768-mh tolerance chart

Why use this? It saves clutter on the drawing. Instead of writing 30 ±0.2 on every single length, you simply rely on the title block standard.

If you are a quality engineer receiving parts with this note, follow these guidelines:

The most critical part of this article is the actual chart. For general tolerances per ISO 2768-1, class Medium (m) , the tolerances are defined by nominal dimension ranges. Note that these are symmetrical tolerances (±) unless otherwise stated. The 'm' stands for Medium accuracy

Angles are treated slightly differently. For Class 'm', the tolerance is expressed in millimeters per millimeter of the shorter side.

Crucial Note: Angular tolerances for untoleranced dimensions are not absolute degrees. They depend on the length of the legs. A short 5mm chamfer at 45° can deviate by 1°, while a long 200mm angled brace can only deviate by 0°5'. If you are a quality engineer receiving parts

For angles without individual tolerances:

| Nominal Angle Range | Permitted Deviation (±) | |---------------------|--------------------------| | Shorter leg ≤ 120 mm | ±1° | | Shorter leg >120 mm | ±0.5° per 120 mm (pro-rated) |

In practice, for most machined parts under 120 mm, you get ±1 degree.