Engineering Reference
ISO 2768 Tolerance Calculator
Enter a nominal dimension and tolerance class. Get the exact permissible deviation from ISO 2768-1 and ISO 2768-2.
Permissible deviation
Out of range
ISO 2768-1 covers 0.5 to 4000mm
Geometrical tolerances (implied)
Source: ISO 2768-2, class K
ISO 2768-1 Linear Tolerances
Permissible deviations for linear dimensions (mm)
| Nominal range (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 |
Looking up tolerances one at a time?
Mavlon applies ISO 2768 tolerances to every untoleranced dimension on your drawing automatically - by size range, not flat defaults.
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Frequently asked questions
What is ISO 2768?
ISO 2768 defines general tolerances for dimensions without individual tolerance indications. Part 1 covers linear and angular dimensions (classes f, m, c, v). Part 2 covers geometrical tolerances (classes H, K, L). The most common aerospace designation is ISO 2768mk (medium linear, K geometrical).
What does ISO 2768-m mean?
ISO 2768-m is the medium tolerance class for linear and angular dimensions. Tolerances vary by nominal dimension size: ±0.1mm for 0.5 to 6mm, ±0.2mm for 6 to 30mm, ±0.3mm for 30 to 120mm, ±0.5mm for 120 to 400mm, ±0.8mm for 400 to 1000mm, and so on.
Are ISO 2768 tolerances size-dependent?
Yes. Unlike flat tolerance blocks on many American drawings, ISO 2768 tolerances change based on the nominal dimension size. A 5mm feature and a 500mm feature on the same drawing get different tolerances. This is the most common error when shops apply ISO 2768 for the first time.
What is the difference between ISO 2768-1 and ISO 2768-2?
ISO 2768-1 defines tolerances for linear and angular dimensions (the "m" in 2768mk). ISO 2768-2 defines tolerances for geometrical characteristics like flatness, perpendicularity, symmetry, and circular runout (the "K" in 2768mk).
Is ISO 2768 still a current standard?
Partly. ISO 2768-2 (geometrical tolerances) has been withdrawn and succeeded by ISO 22081:2021. In practice, huge numbers of legacy and current drawings still invoke ISO 2768 in their title blocks, and the standard that governs your part is the one the drawing references, at the revision it references. This calculator serves those drawings; if your drawing cites ISO 22081 or another general tolerance specification, apply that document instead.