General tolerance calculator
The general tolerance for any dimension, by process: machined, fitted, stamped, cast, moulded or welded. Look up one value or a whole drawing at once.
Single value
Lookup
Applicable table
Reference
Linear dimensions: Below 0.5 mm there is no general tolerance. State the permissible deviation next to the dimension.
Part 2 status: withdrawn. Replaced by ISO 22081:2021. Classes H, K and L remain widely used on legacy drawings. For new drawings use ISO 22081 geometrical specifications.
Angles: Values are shown in decimal degrees; the calculator also shows degrees and minutes, and mm per 100 mm.
Calculated tolerance
Result
Permissible deviation
± 0.30 mm
Class m · over 30 to 120
Applied feature
linear
Nominal 50 mm
| Item | Value |
|---|---|
| Feature | linear |
| Nominal | 50.00 mm |
| Class | m — Medium (the default general class) |
| Applicable range | over 30 to 120 |
| Deviation | ± 0.30 mm |
| Upper limit | 50.30 mm |
| Lower limit | 49.70 mm |
| Status | Permissible deviation |
| Note | — |
ISO 2768-1 and -2
Class reference
| Class | Meaning | When to use |
|---|---|---|
| f / H | Fine | Precision fits, thin sections, low clearance |
| m / K | Medium | Default general tolerance for machined parts |
| c / L | Coarse | Structural or non-critical features |
| v | Very coarse | Rough castings and flame-cut stock |
The relevant table is selected from the nominal size, not the tolerance value. Confirm the drawing uses ISO 2768 before applying this lookup, and state critical tolerances individually.
How this is calculated
How the lookup works
The nominal size selects a row in the ISO 2768-1 table. Only the selected class column is read. For a linear dimension the result is a symmetric tolerance ±t; the upper and lower limits shown are nominal + t and nominal − t.
Angles
ISO 2768-1 angular tolerances are expressed as degrees and minutes, not as a linear millimetre allowance. The calculator also shows the equivalent deviation over 100 mm so you can compare it with a feature length.
Part 2 and ISO 22081
ISO 2768-2:1989 was withdrawn and replaced by ISO 22081:2021. H, K and L are kept in this tool because they still appear on legacy drawings. Do not introduce ISO 2768-2 classes on a new drawing without checking the applicable drawing standard.
Scope and limits
General tolerances do not apply below the tabulated minimum, to reference dimensions, or where an individual tolerance is stated. They do not replace tolerance analysis, fit calculations, geometric tolerance frames or process capability studies.
What is the difference between ISO 2768-f, m, c and v?+
Fine (f), medium (m), coarse (c) and very coarse (v) are general tolerance classes. Medium is the usual default for machined metal parts; fine is used where clearance or function needs tighter control; coarse and very coarse suit structural or non-critical features.
Does ISO 2768 apply to angles in degrees or millimetres?+
The standard gives angular tolerances in degrees and minutes, selected by the shorter leg of the angle. The millimetres-per-100-mm value is an equivalent linear deviation, not the specified value.
Is ISO 2768-2 still current?+
No. ISO 2768-2:1989 was withdrawn and replaced by ISO 22081:2021. The H, K and L classes are included here to help read older drawings.
Can I use this for aerospace or medical parts?+
Only if the drawing or contract invokes ISO 2768. Aerospace, medical and safety-critical work often has its own drawing standard and inspection requirements. Treat this as a drafting aid, not a certification.
Need the drawing checked?
Send it. We come back with DFM notes, a line-by-line costing and a development timeline.
Related tools