ISO 2768 tolerance tables: general tolerances at a glance
All limit deviations of ISO 2768-1 for linear and angular dimensions (classes f, m, c, v) and the geometrical tolerances of ISO 2768-2 (classes H, K, L) — with what belongs to them when inspecting.
If a drawing states “General tolerances ISO 2768-mK”, the table values of the standard apply to all dimensions without an individual tolerance indication. The first letter designates the tolerance class for linear and angular dimensions per ISO 2768-1 (f, m, c or v), the second the class for form and location per ISO 2768-2 (H, K or L). In Switzerland the standard is adopted as SN EN ISO 2768.
ISO 2768-1: limit deviations for linear dimensions
The limit deviations apply per nominal size range, symmetrically as a ± value. For nominal sizes below 0.5 mm, the tolerance must be indicated directly at the dimension.
| Nominal size in mm | f (fine) | m (medium) | c (coarse) | v (very coarse) |
|---|---|---|---|---|
| 0.5 to 3 | ±0.05 | ±0.1 | ±0.2 | — |
| over 3 to 6 | ±0.05 | ±0.1 | ±0.3 | ±0.5 |
| over 6 to 30 | ±0.1 | ±0.2 | ±0.5 | ±1.0 |
| over 30 to 120 | ±0.15 | ±0.3 | ±0.8 | ±1.5 |
| over 120 to 400 | ±0.2 | ±0.5 | ±1.2 | ±2.5 |
| over 400 to 1000 | ±0.3 | ±0.8 | ±2.0 | ±4.0 |
| over 1000 to 2000 | ±0.5 | ±1.2 | ±3.0 | ±6.0 |
| over 2000 to 4000 | — | ±2.0 | ±4.0 | ±8.0 |
Broken edges (chamfers and edge radii) have their own, coarser table:
| Nominal size in mm | f (fine) | m (medium) | c (coarse) | v (very coarse) |
|---|---|---|---|---|
| 0.5 to 3 | ±0.2 | ±0.2 | ±0.4 | ±0.4 |
| over 3 to 6 | ±0.5 | ±0.5 | ±1.0 | ±1.0 |
| over 6 | ±1.0 | ±1.0 | ±2.0 | ±2.0 |
ISO 2768-1: limit deviations for angular dimensions
Decisive is the length of the shorter leg of the angle — not the nominal angle.
| Shorter leg in mm | f (fine) | m (medium) | c (coarse) | v (very coarse) |
|---|---|---|---|---|
| up to 10 | ±1° | ±1° | ±1° 30′ | ±3° |
| over 10 to 50 | ±0° 30′ | ±0° 30′ | ±1° | ±2° |
| over 50 to 120 | ±0° 20′ | ±0° 20′ | ±0° 30′ | ±1° |
| over 120 to 400 | ±0° 10′ | ±0° 10′ | ±0° 15′ | ±0° 30′ |
| over 400 | ±0° 5′ | ±0° 5′ | ±0° 10′ | ±0° 20′ |
ISO 2768-2: form and location — classes H, K, L
Part 2 defines general tolerances for straightness, flatness, perpendicularity, symmetry and run-out. For straightness and flatness, the longer value of the considered line or surface applies:
| Nominal size in mm | H | K | L |
|---|---|---|---|
| up to 10 | 0.02 | 0.05 | 0.1 |
| over 10 to 30 | 0.05 | 0.1 | 0.2 |
| over 30 to 100 | 0.1 | 0.2 | 0.4 |
| over 100 to 300 | 0.2 | 0.4 | 0.8 |
| over 300 to 1000 | 0.3 | 0.6 | 1.2 |
| over 1000 to 3000 | 0.4 | 0.8 | 1.6 |
Perpendicularity — the shorter leg is decisive:
| Shorter leg in mm | H | K | L |
|---|---|---|---|
| up to 100 | 0.2 | 0.4 | 0.6 |
| over 100 to 300 | 0.3 | 0.6 | 1.0 |
| over 300 to 1000 | 0.4 | 0.8 | 1.5 |
| over 1000 to 3000 | 0.5 | 1.0 | 2.0 |
Symmetry — the longer value is decisive:
| Nominal size in mm | H | K | L |
|---|---|---|---|
| up to 100 | 0.5 | 0.6 | 0.6 |
| over 100 to 300 | 0.5 | 0.6 | 1.0 |
| over 300 to 1000 | 0.5 | 0.8 | 1.5 |
| over 1000 to 3000 | 0.5 | 1.0 | 2.0 |
Run-out (circular and axial run-out) is independent of the nominal size: 0.1 mm in class H, 0.2 mm in class K and 0.5 mm in class L.
Is ISO 2768 still valid at all?
Yes — with one important restriction. ISO 2768-1:1989 remains valid; a revision is under way that narrows the scope considerably. What that means for existing drawings with an undated reference is described in a separate article (in German): ISO/FDIS 2768 — why the undated application is critical.
ISO 2768-2:1989 has been replaced by ISO 22081:2021. For new drawings, general geometrical specifications therefore belong in ISO 22081 — with an explicitly stated datum. On countless existing drawings, however, the indication per ISO 2768-2 remains a reality and must be interpreted correctly when inspecting.
What to watch when inspecting
- The general tolerance applies only without an individual indication. As soon as a dimension carries its own tolerance, the table no longer applies to that dimension.
- Clarify the class and the edition. “ISO 2768” without a class or without a date is not an unambiguous specification — and with disputed dimensions, exactly that becomes the problem.
- A general tolerance does not replace function-oriented tolerancing. Function-critical characteristics belong toleranced individually — per ISO GPS with datums and a clear specification, if needed with support in the project.
- Rejection per ISO 2768-1 is not automatic. The standard notes that exceeding the general tolerance does not necessarily lead to rejection if the function is not impaired — this too belongs cleanly agreed rather than silently assumed.
Unclear what really applies on your drawing? CSL reviews drawings for unambiguity, conformity to the standards and verifiability — and measures your parts with a clear conformity decision per characteristic.
