ISO Standard Reference

ISO 2768 — General Tolerances

General tolerances for linear dimensions, angular dimensions, and geometrical tolerances for features not individually toleranced on drawings. Covers both Part 1 (linear & angular) and Part 2 (geometrical).

ISO 2768-1 : Linear & Angular ISO 2768-2 : Geometrical Supersedes DIN 7168
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ISO 2768-1

Part 1 — Linear & Angular Tolerances

Applies to dimensions of metals and other materials manufactured by removal of material. Tolerance classes are designated by a single letter. Indicate on drawing as: ISO 2768-m or ISO 2768-mK (combined with Part 2).

fFine
mMedium — most common default
cCoarse
vVery Coarse
Table 1 — ISO 2768-1 : Tolerances on Linear Dimensions (±mm) — ranges in mm, 0.5¹⁾ up to 4000
Tolerance Class Designation Nominal Length Range (mm)
0.5–3 3–6 6–30 30–120 120–400 400–1000 1000–2000 2000–4000
Fine f ±0.05±0.05±0.1±0.15±0.2±0.3±0.5—
Medium m ±0.1±0.1±0.2±0.3±0.5±0.8±1.2±2
Coarse c ±0.2±0.3±0.5±0.8±1.2±2±3±4
Very Coarse v —±0.5±1±1.5±2.5±4±6±8
Application Note

Class m (medium) is the most widely used default for general machined parts. Class f (fine) is used where closer tolerances are needed but individual tolerancing is not practical. ¹⁾ For nominal sizes below 0.5 mm, deviations shall be indicated adjacent to the relevant nominal size on the drawing — general tolerances do not apply below 0.5 mm.

ISO 2768-1

Table 2 — Tolerances on Broken Edges

Applies to external radii and chamfer heights. These are the dimensions of chamfers, fillets, and rounded edges that are not individually toleranced.

Table 2 — ISO 2768-1 : Tolerances on Broken Edges (±mm)
Tolerance Class Designation 0.5–3 mm 3–6 mm >6 mm
Fine f ±0.2±0.5±1.0
Medium m ±0.2±0.5±1.0
Coarse c ±0.4±1.0±2.0
Very Coarse v ±0.4±1.0±2.0
Note

Classes f and m share identical values for broken edges. The distinction between these classes only matters for linear and angular dimensions. Note the three ranges: 0.5–3 mm, over 3 up to 6 mm, and over 6 mm.

ISO 2768-1

Table 3 — Tolerances on Angular Dimensions

Angular tolerances are expressed as ± values in degrees and minutes (°′). The tolerance applies to the shorter side of the angle. Ranges are based on the length of the shorter side of the angle in mm.

Table 3 — ISO 2768-1 : Tolerances on Angular Dimensions
Tolerance Class Designation up to 10 mm 10–50 mm 50–120 mm 120–400 mm >400 mm
Fine f ±1°±0°30′±0°20′±0°10′±0°5′
Medium m ±1°±0°30′±0°20′±0°10′±0°5′
Coarse c ±1°30′±1°±0°30′±0°15′±0°10′
Very Coarse v ±3°±2°±1°±0°30′±0°20′
Application Note

Classes f and m share identical values for angular tolerances. Angular tolerances decrease (tighten) as the length of the shorter side increases, because the same angular deviation produces a larger linear displacement on longer arms.

ISO 2768-2

Part 2 — Geometrical Tolerances

Defines general geometrical tolerances for features not individually toleranced. Three tolerance classes: H (fine), K (medium), L (coarse). Indication: ISO 2768-K or combined: ISO 2768-mK.

HFine
KMedium — most common default
LCoarse

Table 1 — Tolerances on Flatness and Straightness

Values apply to the longer side or the diameter of the surface. All values in mm.

Table 1 — ISO 2768-2 : Flatness and Straightness Tolerances (mm)
Tolerance Class Nominal Length Range (mm)
up to 10 10–30 30–100 100–300 300–1000 1000–3000
H — Fine 0.020.050.100.200.300.40
K — Medium 0.050.100.200.400.600.80
L — Coarse 0.100.200.400.801.201.60
ISO 2768-2

Table 2 — Tolerances on Perpendicularity

Applies to surfaces and edges that should be perpendicular (90°) to a reference. The nominal range is the length of the shorter side. All values in mm.

Table 2 — ISO 2768-2 : Perpendicularity Tolerances (mm)
Tolerance Class Nominal Length Range of Shorter Side (mm)
up to 100 100–300 300–1000 1000–3000
H — Fine 0.200.300.400.50
K — Medium 0.400.600.801.00
L — Coarse 0.601.001.502.00
Important Distinction

The perpendicularity tolerance from ISO 2768-2 applies to untoleranced features. When a feature has an explicit GD&T perpendicularity callout (⊥), that value takes precedence. ISO 2768-2 is only the fallback for features with no individual geometric tolerance.

ISO 2768-2

Table 3 — Tolerances on Symmetry

Applies to the symmetrical relationship between features. The nominal range is based on the longer of the two dimensions involved. All values in mm.

Table 3 — ISO 2768-2 : Symmetry Tolerances (mm)
Tolerance Class Nominal Length Range (mm)
up to 100 100–300 300–1000 1000–3000
H — Fine 0.5
K — Medium 0.6 0.8 1
L — Coarse 0.6 1 1.5 2

H = 0.5 mm for all length ranges. K = 0.6 mm for up to 300 mm (merged), then 0.8 and 1.0 mm.

ISO 2768-2

Table 4 — Tolerances on Circular Run-Out

Applies to circular run-out of surfaces of revolution about an axis. Run-out is measured as the total indicator movement (TIM) during one full revolution. This is a single value (not range-dependent). All values in mm.

Table 4 — ISO 2768-2 : Circular Run-Out Tolerances (mm)
Tolerance Class Designation Run-Out Tolerance (mm) Typical Application
H Fine 0.1 Precision rotating parts, spindles, precision shafts
K Medium 0.2 General machined rotating parts
L Coarse 0.5 Non-critical rotating features, cast or forged parts
Run-Out vs Total Run-Out

ISO 2768-2 specifies circular run-out only (measured at a single cross-section). Total run-out (full surface) is a more stringent requirement and must always be individually toleranced with a GD&T callout — it is not covered by general tolerances.

Combined Notation

ISO 2768 allows combining Part 1 and Part 2 in a single title block entry. Examples:
ISO 2768-f — Part 1 Fine only
ISO 2768-mK — Part 1 Medium + Part 2 Medium (most common)
ISO 2768-fH — Part 1 Fine + Part 2 Fine (precision parts)
ISO 2768-cL — Part 1 Coarse + Part 2 Coarse (rough fabrication)