Nominal size

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Nominal dimensions are numerical data on technical drawings and other construction and site plans that define the mathematical distance between two measurement or construction reference points . In contrast to the actually measured actual dimensions , they indicate the planned dimensions.

As a dimension , the nominal dimension is a size that, taking into account the tolerance information, serves to determine the permissible limit dimensions of a component or an assembly . The limit dimensions are the maximum or largest dimension and the minimum or smallest dimension between which the actual dimension of a workpiece must lie. The limit dimensions are usually specified by the designer with tolerance specifications on the drawing . The value in the middle of the tolerance field is called the nominal dimension . As a rule, the nominal dimension corresponds to the nominal dimension. It happens, however, that these two values ​​differ from one another, namely in the case of one-sided tolerance, e.g. B. . The nominal dimension here is 150.2 mm with a tolerance of ± 0.05 mm. This procedure results from the unresolved contradiction between nominal dimensions, which are as integer as possible, and nominal dimensions as nominal dimensions.


  • DIN EN ISO 286 - Geometrical product specification, ISO tolerance system for linear dimensions