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General Tolerances Calculator — ISO 2768-1
Look up general tolerance values per ISO 2768-1 by tolerance class and nominal dimension. Linear and angular tolerances with full reference tables.
Results
Table 1 — Linear Dimensions (Permissible Deviations in mm)
| Range (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 |
Table 2 — Angular Dimensions (Permissible Deviations)
| Shorter Side (mm) | f (Fine) | m (Medium) | c (Coarse) | v (Very Coarse) |
|---|---|---|---|---|
| ≤ 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′ |
ℹ️ Note: ISO 2768-1 applies to all dimensions on the drawing that do not have individual tolerances specified. The tolerance class letter is placed in the title block, e.g. “ISO 2768-m”.
What Are General Tolerances?
General tolerances per ISO 2768-1 define permissible deviations for linear and angular dimensions that do not carry individual tolerance indications on a drawing. They represent normal workshop accuracy achievable with standard machining processes.
The actual dimension must fall within the range:
Tolerance Class Selection
- f (Fine) — Precision machining, tight fits. Requires careful process control.
- m (Medium) — Most commonly used. Standard machining (turning, milling, drilling).
- c (Coarse) — Rough machining, welded structures, non-critical parts.
- v (Very Coarse) — Castings, flame-cut parts, forgings.
Drawing Notation
For linear tolerances only: ISO 2768-m
Combined with geometrical tolerances (ISO 2768-2): ISO 2768-mK
This means: linear tolerance class “m” + geometrical tolerance class “K”.
⚠️ Important: General tolerances do not apply to dimensions with individual tolerances, reference dimensions (in parentheses), or dimensions governed by other standards.
ISO 2768 is an international standard that defines general tolerances for linear and angular dimensions on engineering drawings. Part 1 (ISO 2768-1) covers linear and angular tolerances, while Part 2 (ISO 2768-2) covers geometrical tolerances.
General tolerances apply to all dimensions on a drawing that do not have individual tolerances indicated. This simplifies drawings and reduces the number of tolerance notations needed.
General tolerances are appropriate when:
- Features are produced by standard machining (turning, milling, drilling)
- Normal workshop accuracy is sufficient for function
- Parts do not require tight fits or precision alignment
Do not rely on general tolerances for critical fits, mating surfaces, seal grooves, or bearing seats — these require individual tolerances.
The four tolerance classes represent increasing levels of permissible deviation:
- f (Fine) — Tightest tolerances. Precision machining with careful process control.
- m (Medium) — Most commonly used. Standard machining accuracy.
- c (Coarse) — Rough machining, welded assemblies, non-critical parts.
- v (Very Coarse) — Castings, forgings, flame-cut parts.
When in doubt, class m is the default for general machined parts.
Angular tolerances per ISO 2768-1 Table 2 depend on the shorter side of the angle being toleranced. As the shorter side length increases, the angular tolerance decreases (tighter).
For example, for class m: a 5 mm side gets ±1°, while a 200 mm side gets ±0°10′. The tolerance is given in degrees and minutes of arc.
Place the standard designation in the title block of the drawing:
- ISO 2768-m — Linear tolerances only, class m
- ISO 2768-mK — Linear class m + geometrical class K (ISO 2768-2)
- ISO 2768-fH — Linear class f + geometrical class H
No additional notation is needed on individual dimensions — the general tolerance automatically applies to all untoleranced dimensions.
The procedures described on this page were developed and field-tested by the Vibromera team using the Balanset-1A, a portable dual-channel balancer and vibration analyzer for on-site rotor balancing.
Professional field balancing instruments and software. Used in 50+ countries.
Nikolai Shelkovenko
Nikolai Shelkovenko is a vibration analysis engineer and the founder and CEO of Vibromera. For more than 15 years he has balanced rotating equipment in the field rather than on a test bench: mulchers, industrial fans, crushers, centrifuges, shafts and spindles. That work is what the Balanset instruments grew out of — they were designed as a tool a specialist can carry to the machine and use alone, on site, not as laboratory equipment. Vibromera was founded in 2017 and has been based in Porto, Portugal, since 2023. Development, assembly and support of the Balanset line all happen here. The flagship instrument is the Balanset-1A, a portable analyser for single- and two-plane balancing and for vibration diagnostics. Nikolai is personally involved in customer support, in working through difficult balancing cases and in the development of the software. He works with customers worldwide, in any language.
