General Tolerance – ISO 2768

Part 1

ISO 2768-1 is intended to simplify drawing indications and specifies general tolerances in 4 tolerance classes (f – fine, m – medium, c – coarse, v – very coarse). It applies for the linear dimensions and angular dimensions such as external sizes, internal sizes, step sizes, diameters, radii, distances, external radii, and chamfer heights for broken edges.
 
If general tolerances in accordance with ISO 2768 shall apply, ISO 2768 followed by the tolerance class (Ex: ISO 2768-m) shall be indicated in or near the title block.

The following is the tolerance table corresponding to the 4 class precision levels, you can choose the most suitable one according to machining capabilities and your design requirements.

Table 1 - Linear Dimensions

Permissible deviations in mm for ranges in nominal lengthsTolerance Class Designation (Description)
f (fine)m (medium)c (coarse)v (very coarse)
0.5 up to 3±0.05±0.1±0.2
over 3 up to 6±0.05±0.1±0.3±0.5
over 6 up to 30±0.1±0.2±0.5±1.0
over 30 up to 120±0.15±0.3±0.8±1.5
over 120 up to 400±0.2±0.5±1.2±2.5
over 400 up to 1000±0.3±0.8±2.0±4.0
over 1000 up to 2000±0.5±1.2±3.0±6.0
over 2000 up to 4000±2.0±4.0±8.0

For nominal sizes below 0.5 mm, the deviations shall be indicated adjacent to the relevant nominal size(s).

Table 2 - External Radii and Chamfer Heights

Permissible deviations in mm for ranges in nominal lengthsTolerance Class Designation (Description)
f (fine)m (medium)c (coarse)v (very coarse)
0.5 up to 3±02±0.2±0.4±0.4
over 3 up to 6±0.5±0.5±1.0±1.0
over 6±1.0±1.0±2.0±2.0

For nominal sizes below 0.5 mm, the deviations shall be indicated adjacent to the relevant nominal size(s).

Table 3 - Angular Dimensions

Permissible deviations in mm for ranges in nominal lengthsTolerance Class Designation (Description)
f (fine)m (medium)c (coarse)v (very coarse)
up to 10±1º±1º±1º30′±3º
over 10 up to 50±0º30′±0º30′±1º±2º
over 50 up to 120±0º20′±0º20′±0º30′±1º
over 120 up to 400±0º10′±0º10′±0º15′±0º30′
over 400±0º5′±0º5′±0º10′±0º20′

Part 2

ISO 2768-2 is for simplifying drawing and fixing general tolerances in three tolerance classes (H, K, and L), with this part including General Geometrical Tolerances for flatness and straightness, cylindricity, and circularity. Check out the tolerance chart below:

Table 4 - General Tolerances on Straightness and Flatness

Ranges of nominal lengths in mmTolerance Class
HKL
up to 100.020.050.1
above 10 to 300.050.10.2
above 30 to 1000.10.20.4
above 100 to 3000.20.40.8
above 300 to 10000.30.61.2
above 1000 to 30000.40.81.6

Table 5 - General Tolerances on Perpendicularity

Ranges of nominal lengths in mmTolerance Class
HKL
up to 1000.20.40.6
above 100 to 3000.30.61.0
above 300 to 10000.40.81.5
above 1000 to 30000.51.02.0

Table 6 - General Tolerances on Symmetry

Ranges of nominal lengths in mmTolerance Class
HKL
up to 1000.50.60.6
above 100 to 3000.50.61.0
above 300 to 10000.50.81.5
above 1000 to 30000.51.02.0

Table 7 - General Tolerances on Circular Run-Out

Ranges of nominal lengths in mmTolerance Class
HKL
0.10.20.5
Scroll to Top