What is the Perpendicularity symbol in GD&T?

⟂ — Unicode U+27C2 (PERPENDICULAR). It goes in the first compartment of the feature control frame, ahead of the tolerance value.

Does Perpendicularity need a datum?

Always references at least one datum. Without a datum reference frame the callout is incomplete and the drawing is ambiguous.

What shape is the Perpendicularity tolerance zone?

Two parallel planes (or a cylinder, for an axis) normal to the datum. Every point of the controlled feature has to lie inside that zone for the part to pass.

Which GD&T controls are in the same group as Perpendicularity?

Perpendicularity is one of 3 orientation controls: Perpendicularity, Angularity, Parallelism.

GD&T · Orientation · ASME Y14.5

Perpendicularity GD&T Symbol — Meaning and Datum Rule

https://shopmath.org/gdt/perpendicularity · data verified August 1, 2026

Perpendicularity (⟂) is a GD&T orientation control, and its tolerance zone is two parallel planes (or a cylinder, for an axis) normal to the datum. It always references a datum.

Symbol: ⟂
Unicode: U+27C2
Category: Orientation
Datum: always

Perpendicularity · GD&T orientation symbol

⟂

Unicode: U+27C2
Datum: always
Zone: Two parallel planes (or a cylinder, for an axis) normal to the datum

The value in the feature control frame is the width or diameter of that zone, in the drawing's units.

What Perpendicularity Controls in GD&T

Angularity's ninety-degree special case. Applied to a surface the zone is two planes square to the datum; applied to a hole or pin axis with a diameter symbol the zone is a cylinder square to the datum, which is the form usually wanted for a bolt hole in a machined face.

The Perpendicularity GD&T Symbol, Zone and Datum Rule

The symbol as it appears in the feature control frame, with the codepoint to type it and the rule it carries.

Perpendicularity — GD&T symbol, tolerance zone and datum rule
Property	Value
Symbol	⟂
Unicode codepoint	U+27C2 (PERPENDICULAR)
Category	Orientation controls — Control the angle of a feature relative to a datum, but not its distance.
Tolerance zone	Two parallel planes (or a cylinder, for an axis) normal to the datum
Datum reference	Always references at least one datum. Without a datum reference frame the callout is incomplete and the drawing is ambiguous.
Standard	ASME Y14.5 (cited, not reproduced); ISO 1101
Also called	squareness

The symbol character is the Unicode codepoint used in drawings and CAD annotations; drafting standards render it with defined proportions that the font approximates.

GD&T Controls Related to Perpendicularity

Perpendicularity is a orientation control. Control the angle of a feature relative to a datum, but not its distance. These are the others in that group — the ones a drawing usually chooses between.

GD&T orientation symbols related to Perpendicularity
Symbol	Datum	Tolerance zone
Angularity	always	Two parallel planes (or a cylinder, for an axis) at the basic angle
Parallelism	always	Two parallel planes (or a cylinder, for an axis) parallel to the datum

Ordered as they appear in the feature control frame reference, form through runout, then modifiers.

Sources and Method for the Perpendicularity GD&T Reference

Perpendicularity symbol and rulescompiled

Symbols and codepoints: Unicode Character Database (Unicode License v3). Characteristic list cross-checked against NASA MSFC GD&T Basics (public domain). Descriptions written from scratch; no ASME Y14.5 text reproduced.

Verified against Unicode Character Database codepoint check; 98/98 structural checks passed

Compiled from independent public sources that agree cell-for-cell.

Assumptions

The standard is cited, never reproduced: no ASME Y14.5 definitional text, worked example or figure appears on this site. The description above is original prose.
ASME Y14.5 and ISO 1101 differ in places — the ISO system uses the envelope requirement differently and does not carry every ASME modifier. Where a drawing names a standard, that standard governs.
Dataset scope: EXCLUDED: all ASME Y14.5 definitional text, worked examples and figures. Every description on this site is original prose.

Data last verified

August 1, 2026

How this data is built and checked →

How to Cite This Perpendicularity GD&T Reference

Citation

ShopMath. "Perpendicularity GD&T Symbol — Meaning and Datum Rule." ShopMath, verified August 1, 2026, https://shopmath.org/gdt/perpendicularity

BibTeX

@misc{shopmath-gdt-perpendicularity,
  title        = {Perpendicularity GD&T Symbol — Meaning and Datum Rule},
  author       = {{ShopMath}},
  year         = {2026},
  howpublished = {\url{https://shopmath.org/gdt/perpendicularity}},
  note         = {Data verified 2026-08-01}
}

Permanent URL

https://shopmath.org/gdt/perpendicularity

Common Questions About Perpendicularity in GD&T

What does Perpendicularity mean in GD&T?: Angularity's ninety-degree special case. Applied to a surface the zone is two planes square to the datum; applied to a hole or pin axis with a diameter symbol the zone is a cylinder square to the datum, which is the form usually wanted for a bolt hole in a machined face.
What is the Perpendicularity symbol in GD&T?: ⟂ — Unicode U+27C2 (PERPENDICULAR). It goes in the first compartment of the feature control frame, ahead of the tolerance value.
Does Perpendicularity need a datum?: Always references at least one datum. Without a datum reference frame the callout is incomplete and the drawing is ambiguous.
What shape is the Perpendicularity tolerance zone?: Two parallel planes (or a cylinder, for an axis) normal to the datum. Every point of the controlled feature has to lie inside that zone for the part to pass.
Which GD&T controls are in the same group as Perpendicularity?: Perpendicularity is one of 3 orientation controls: Perpendicularity, Angularity, Parallelism.

Every GD&T symbol and modifier