General tolerances (ISO 2768)
Under ISO 2768-m (medium), a 50 mm untoleranced linear dimension carries ±0.3 mm — that is 49.7 to 50.3 mm without a single tolerance drawn on the print. This page returns the general tolerance for any nominal dimension by class (f, m, c, v) and feature type, from ISO 2768-1 (linear and angular) and ISO 2768-2 (geometrical).
A title-block note like “ISO 2768-mK” sets the class that applies to every dimension carrying no explicit tolerance. The band widens with the nominal size, so the same class gives ±0.1 mm at 3 mm and ±0.8 mm at 1000 mm.
Enter a nominal dimension covered by the selected class and type.
ISO 2768 class m — Linear across nominal ranges
| Nominal range | Tolerance |
|---|
Rows shown for the selected class and type. Change class or type above to see its band; the full text of the standard remains the authority.
What does an ISO 2768 class mean?
ISO 2768-1 defines four tolerance classes for linear and angular dimensions — f (fine), m (medium), c (coarse), and v (very coarse) — each a table of ± values banded by nominal size. A drawing invokes one class in the title block so that dimensions without their own tolerance are still controlled, rather than left open.
ISO 2768-2 adds general geometrical tolerances (straightness, flatness, perpendicularity, symmetry, runout) in three classes H, K, L. A callout such as ISO 2768-mK means class m for size and class K for form and geometry.
How does DIN 7168 relate to ISO 2768?
DIN 7168 is the German predecessor that ISO 2768 superseded; its medium/coarse tables are close to ISO 2768-m/-c, so older prints citing DIN 7168 read across almost directly. This page shows both so a legacy callout can be checked against the current standard, but for new work ISO 2768 governs.