ISO 2768 general tolerances: f, m, c, v and H, K, L
ISO 2768 sets tolerances for every dimension on a drawing that has no tolerance of its own. One line in the title block, for example ISO 2768-mK, covers all of them.
Linear dimensions (ISO 2768-1)
| Nominal size (mm) | f (fine) | m (medium) | c (coarse) | v (very coarse) |
|---|
| 0.5–3 | ±0.05 | ±0.1 | ±0.2 | — |
| >3–6 | ±0.05 | ±0.1 | ±0.3 | ±0.5 |
| >6–30 | ±0.1 | ±0.2 | ±0.5 | ±1 |
| >30–120 | ±0.15 | ±0.3 | ±0.8 | ±1.5 |
| >120–400 | ±0.2 | ±0.5 | ±1.2 | ±2.5 |
| >400–1000 | ±0.3 | ±0.8 | ±2 | ±4 |
| >1000–2000 | ±0.5 | ±1.2 | ±3 | ±6 |
| >2000–4000 | — | ±2 | ±4 | ±8 |
External radii and chamfer heights
| Nominal size (mm) | f | m | c | v |
|---|
| 0.5–3 | ±0.2 | ±0.2 | ±0.4 | ±0.4 |
| >3–6 | ±0.5 | ±0.5 | ±1 | ±1 |
| >6 | ±1 | ±1 | ±2 | ±2 |
Angular dimensions
| Length of shorter leg (mm) | f | m | c | v |
|---|
| up to 10 | ±1° | ±1° | ±1°30′ | ±3° |
| >10–50 | ±0°30′ | ±0°30′ | ±1° | ±2° |
| >50–120 | ±0°20′ | ±0°20′ | ±0°30′ | ±1° |
| >120–400 | ±0°10′ | ±0°10′ | ±0°15′ | ±0°30′ |
| >400 | ±0°5′ | ±0°5′ | ±0°10′ | ±0°20′ |
Straightness and flatness (ISO 2768-2)
| Nominal length (mm) | H | K | L |
|---|
| up to 10 | 0.02 | 0.05 | 0.1 |
| >10–30 | 0.05 | 0.1 | 0.2 |
| >30–100 | 0.1 | 0.2 | 0.4 |
| >100–300 | 0.2 | 0.4 | 0.8 |
| >300–1000 | 0.3 | 0.6 | 1.2 |
| >1000–3000 | 0.4 | 0.8 | 1.6 |
Perpendicularity (ISO 2768-2)
| Shorter side (mm) | H | K | L |
|---|
| up to 100 | 0.2 | 0.4 | 0.6 |
| >100–300 | 0.3 | 0.6 | 1 |
| >300–1000 | 0.4 | 0.8 | 1.5 |
| >1000–3000 | 0.5 | 1 | 2 |
How to use it
Write the class in the title block, for example ISO 2768-mK: medium for sizes and angles, K for geometric tolerances. mK is the common default for machined parts; fH is for precise small parts and costs more; cL suits welded or rough parts. Features that need tighter control get their own tolerance or an ISO fit.
ISO 2768 has been withdrawn in favour of ISO 22081, but it is still the most widely used general tolerance reference on drawings in Europe and widely understood by shops.
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