What is the Cylindricity symbol in GD&T?

⌭ — Unicode U+232D (CYLINDRICITY). It goes in the first compartment of the feature control frame, ahead of the tolerance value.

Does Cylindricity need a datum?

Never references a datum. The tolerance zone floats to best-fit the feature, so this control says nothing about where the feature sits relative to anything else.

What shape is the Cylindricity tolerance zone?

Two coaxial cylinders. 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 Cylindricity?

Cylindricity is one of 4 form controls: Cylindricity, Straightness, Flatness, Circularity.

GD&T · Form · ASME Y14.5

Cylindricity GD&T Symbol — Meaning and Datum Rule

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

Cylindricity (⌭) is a GD&T form control, and its tolerance zone is two coaxial cylinders. It never references a datum.

Symbol: ⌭
Unicode: U+232D
Category: Form
Datum: never

Cylindricity · GD&T form symbol

⌭

Unicode: U+232D
Datum: never
Zone: Two coaxial cylinders

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

What Cylindricity Controls in GD&T

The whole-surface version of circularity. Every point on the cylindrical surface must fall between two coaxial cylinders separated radially by the tolerance value, so one callout simultaneously limits roundness, straightness of the axis, and taper along the length.

The Cylindricity 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.

Cylindricity — GD&T symbol, tolerance zone and datum rule
Property	Value
Symbol	⌭
Unicode codepoint	U+232D (CYLINDRICITY)
Category	Form controls — Control the shape of a single feature against itself. Never reference a datum.
Tolerance zone	Two coaxial cylinders
Datum reference	Never references a datum. The tolerance zone floats to best-fit the feature, so this control says nothing about where the feature sits relative to anything else.
Standard	ASME Y14.5 (cited, not reproduced); ISO 1101
Also called	cylindricity vs circularity

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 Cylindricity

Cylindricity is a form control. Control the shape of a single feature against itself. Never reference a datum. These are the others in that group — the ones a drawing usually chooses between.

GD&T form symbols related to Cylindricity
Symbol	Datum	Tolerance zone
Straightness	never	Two parallel lines (surface element) or a cylinder (axis)
Flatness	never	Two parallel planes
Circularity	never	Two concentric circles in each cross-section

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

Sources and Method for the Cylindricity GD&T Reference

Cylindricity 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 Cylindricity GD&T Reference

Citation

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

BibTeX

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

Permanent URL

https://shopmath.org/gdt/cylindricity

Common Questions About Cylindricity in GD&T

What does Cylindricity mean in GD&T?: The whole-surface version of circularity. Every point on the cylindrical surface must fall between two coaxial cylinders separated radially by the tolerance value, so one callout simultaneously limits roundness, straightness of the axis, and taper along the length.
What is the Cylindricity symbol in GD&T?: ⌭ — Unicode U+232D (CYLINDRICITY). It goes in the first compartment of the feature control frame, ahead of the tolerance value.
Does Cylindricity need a datum?: Never references a datum. The tolerance zone floats to best-fit the feature, so this control says nothing about where the feature sits relative to anything else.
What shape is the Cylindricity tolerance zone?: Two coaxial cylinders. 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 Cylindricity?: Cylindricity is one of 4 form controls: Cylindricity, Straightness, Flatness, Circularity.

Every GD&T symbol and modifier