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Perpendicularity Tolerance


Perpendicularity is the condition of a surface, centre plane, or axis that is exactly at a right angle to a datum plane or datum axis.

A perpendicularity control is a geometric tolerance that limits the amount of surface, axis, or centre-plane is permitted to vary from being perpendicular to the datum. Perpendicularity is a 3D tolerance control. Perpendicularity applied to a plane surface also controls the flatness of that surface. Thus, if no flatness is specified, the flatness tolerance will be as close as the perpendicularity.


If symbol φ is attached before the numerical value indicating the tolerance range, this tolerance range is the range contained within a cylinder of diameter t that is perpendicular to the datum plane.

The axis of the cylinder shown by the arrow of the indicator line shall be contained within a cylinder of diameter 0.01mm that is perpendicular to the datum plane A.


A perpendicularity tolerance specifies one of the following types of tolerance zones:

  • A tolerance zone defined by two parallel planes perpendicular to a datum plan, or axis, within which the surface or centre plane of the considered feature must lie.
  • A tolerance zone defined by two parallel planes perpendicular to a datum axis, within which the axis of the considered feature must lie
  • A cylindrical tolerance zone perpendicular to a datum plan within which the axis of the considered feature must lie
  • A tolerance zone defined by two parallel lines perpendicular to a datum, plane, or axis, within which, the elements of the surface must lie
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