ISO 2768 General Tolerance Calculator
Work it out in either direction: find the permitted deviation for a dimension — or start from the tolerance you actually need and find out whether the general tolerance already covers it, or whether you must call it out on the drawing. Covers ISO 2768-1 (linear, radii, angular) and ISO 2768-2 (geometrical). No sign-up.
In mm. For angular, enter the length of the shorter side.
The question that actually matters on a drawing: do I need to specify this, or is it covered already?
Enter the half-width, e.g. for 120 ±0.15 enter 0.15.
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Related: Material selector · CNC Milling · CNC Turning · Finishing & Inspection
How ISO 2768 general tolerances work
Every dimension on a drawing needs a tolerance. Writing one against all of them is tedious and clutters the drawing, so ISO 2768 lets you declare a single general tolerance class — usually in or near the title block — that applies automatically to any dimension without an individual tolerance shown. You then only call out the features that genuinely need to be tighter.
ISO 2768-1 covers linear and angular dimensions in four classes: f (fine), m (medium), c (coarse) and v (very coarse). The permitted deviation widens with the size of the feature — 2768-f allows ±0.05 mm on a 3 mm dimension but ±0.2 mm by the time you reach 400 mm. ISO 2768-2 covers geometrical tolerances — straightness and flatness, perpendicularity, symmetry and circular runout — in three classes: H, K and L. A callout like ISO 2768-mK simply combines the two: medium for dimensions, K for geometry.
The question this calculator is really built for is the reverse one. Engineers rarely need to know what 2768-f permits at 120 mm in the abstract — they need to know whether the ±0.05 mm they have in mind is already covered by the general note, or whether it has to be explicitly toleranced on the face of the drawing. Get that wrong in the loose direction and you receive parts that are in spec but useless; get it wrong in the tight direction and you pay for precision you never needed. The reverse tab answers it directly.
Our standard is ISO 2768-f across CNC milling and turning, at ±0.010 mm standard precision on most materials. Tighter tolerances on critical features can be agreed at quotation stage for specific geometries — if a feature matters, say so and we will confirm it explicitly rather than leave it to a general note.
ISO 2768 general tolerances — FAQ
What is ISO 2768?
ISO 2768 is the standard for general tolerances — the tolerances that apply to any dimension on a drawing that has no individual tolerance shown against it. Part 1 covers linear and angular dimensions in four classes (f fine, m medium, c coarse, v very coarse). Part 2 covers geometrical tolerances (flatness, perpendicularity, symmetry, runout) in three classes (H, K, L).
What does ISO 2768-mK mean?
It is two classes at once: "m" is the medium class for linear and angular dimensions from Part 1, and "K" is the middle class for geometrical tolerances from Part 2. It is one of the most common general-tolerance callouts on engineering drawings.
What is the tolerance for ISO 2768-f?
It depends on the size of the feature. For linear dimensions, 2768-f permits ±0.05 mm up to 3 mm, ±0.1 mm from 6–30 mm, ±0.15 mm from 30–120 mm and ±0.2 mm from 120–400 mm. ISO 2768-f is our standard across CNC milling and turning.
Do I need to tolerance every dimension on a drawing?
No — that is the point of ISO 2768. Put the general tolerance class in or near the title block and it applies to every dimension without an individual tolerance. You then only call out the features that need to be tighter than the general class. Use the reverse mode above to check whether a dimension actually needs calling out.
What tolerance can CNC machining hold?
Our standard precision is ±0.010 mm (ISO 2768-f) across most materials on 3, 4 and 5-axis milling and CNC turning. Tighter tolerances on critical features can be agreed at quotation stage for specific geometries. Engineering plastics are wider because of thermal dimensional instability.
Is ISO 2768 the same as DIN ISO 2768?
Effectively yes — DIN ISO 2768 is the German adoption of the same standard, and the tolerance tables are identical. You will see drawings marked either way.