Note: Perpendicularity does not control the angle of the referenced feature –the tolerance is in distance units. See the tolerance zone below for more details. The tolerance of the perpendicularity callout indirectly controls the 90° angle between the parts by controlling the location where the surfaces have to lie.

Perpendicularity can reference a 2D line, but more commonly it describes the orientation of one surface plane perpendicular to another datum plane. Perpendicularity is a fairly common symbol that requires the referenced surface or line to be perpendicular or 90° from a datum surface or line. Relative to Datum: Yes MMC or LMC applicable: Yes GD&T Drawing Callout: Surface Perpendicularity: Pay close attention if a hole or pin is referenced since axis perpendicularity is commonly called out on these features. Axis Perpendicularity is controlled by a cylinder around a theoretical perfectly parallel axis. Axis Perpendicularity is a tolerance that controls how perpendicular a specific axis needs to be to a datum. Surface Perpendicularity is controlled with two parallel planes acting as its tolerance zone. The normal form or Surface Perpendicularity is a tolerance that controls Perpendicularity between two 90° surfaces, or features. Perpendicularity in Geometric Dimensioning and Tolerancing can mean two very different things depending on which reference feature is called out.

Datum reference frame