ISO 2768 is an international standard created by the International Organization for Standardization. It provides a set of general tolerances for linear and angular dimensions without individual tolerance indications.
Under ISO 2768-1, there are four tolerance classes: f (fine), m (medium), c (coarse), and v (very coarse). The class is the most frequently used in general mechanical engineering. Linear Dimensions (mm)
If you’ve seen "ISO 2768-mk" in the title block of a blueprint, What is ISO 2768? general tolerance iso 2768-mk
It provides a universal language between designers and manufacturers worldwide, ensuring that a part made in Germany fits a part made in the USA. When NOT to use it
Parts made from plastics or materials with high thermal expansion (the standard is primarily designed for metal removal/machining). Dimensions where safety or critical function is at stake. ISO 2768 is an international standard created by
ISO 2768-mk is a "general" standard. You should never rely on it for: High-precision fits (e.g., H7/g6).
It keeps drawings clean. Only critical dimensions (like a bearing fit or a sealing surface) need specific ± tolerances. The class is the most frequently used in
It signals to the machine shop that standard workshop accuracy is sufficient for non-critical areas, preventing over-processing and reducing costs.