Nominal dimension

Nominal dimensions are the labels on Design drawings, building plans and layout plans that depict the distance between two points of reference in the design.

A designer will specify the permissible limit sizes for a component - its minimum and maximum dimensions - using the nominal dimension and a dimensional Tolerance. The designer will also indicate the extent of the tolerance (e.g. $\pm 0.05$) in the drawing. The Actual dimension of the workpiece must fall inside this range. The target dimension is in the middle, between the minimum and maximum dimensions. The target dimension is usually the same as the nominal dimension. However it can also deviate from this dimension in the case of one-sided tolerance (e.g. $+0.05$).