---
type: "gdt-symbol"
name: "Cylindricity"
symbol: "⌭"
unicode: "U+232D"
unicode_name: "CYLINDRICITY"
category: "form"
category_name: "Form controls"
datum_required: "never"
tolerance_zone: "Two coaxial cylinders"
aliases: ["cylindricity gdt", "cylindricity vs circularity"]
standard: "ASME Y14.5 (cited, not reproduced); ISO 1101"
verified: "August 1, 2026"
url: https://shopmath.org/gdt/cylindricity
---

# Cylindricity (⌭) — GD&T Symbol, Tolerance Zone and Datum Rules

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.

- **Symbol**: ⌭ (Unicode U+232D)
- **Category**: Form controls
- **Tolerance zone**: Two coaxial cylinders
- **Datum reference**: never references a datum
- **Standard**: ASME Y14.5 (cited, not reproduced); ISO 1101

## Cylindricity at a Glance

| Property | Value |
| --- | --- |
| Characteristic | Cylindricity |
| Symbol | ⌭ |
| Unicode codepoint | U+232D |
| Unicode name | CYLINDRICITY |
| Category | Form controls |
| Tolerance zone | Two coaxial cylinders |
| Datum reference | never references a datum |
| Standard | ASME Y14.5 (cited, not reproduced); ISO 1101 |

## How Cylindricity Behaves

Cylindricity belongs to the form controls group. Control the shape of a single feature against itself. Never reference a datum.

## Other Form controls Controls

The controls in the same category — the ones a drawing is choosing between when it specifies cylindricity.

| Control | Symbol | Tolerance zone or effect | Datum |
| --- | --- | --- | --- |
| [Straightness](https://shopmath.org/gdt/straightness.md) | ⏤ | Two parallel lines (surface element) or a cylinder (axis) | never references a datum |
| [Flatness](https://shopmath.org/gdt/flatness.md) | ⏥ | Two parallel planes | never references a datum |
| [Circularity](https://shopmath.org/gdt/circularity.md) | ○ | Two concentric circles in each cross-section | never references a datum |

## Sources and Method for Cylindricity

### Cylindricity definition

- **Source**: 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.
- **Method**: compiled
- **Verified against**: Unicode Character Database codepoint check; 98/98 structural checks passed

### Assumptions

- Descriptions are original prose. No ASME Y14.5 definitional text, worked example or figure is reproduced — the standard is cited, not copied.
- Symbol glyphs and codepoints are from the Unicode Character Database; a drawing may render the same characteristic with a different font.
- 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

## 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 GD&T symbol for cylindricity?

Cylindricity uses the ⌭ symbol — Unicode U+232D (CYLINDRICITY). It sits in the first compartment of the feature control frame.

### Does Cylindricity need a datum?

Cylindricity never references a datum. The tolerance zone floats to best-fit the feature, so there is nothing to reference it to.

### What is the tolerance zone for Cylindricity in GD&T?

The cylindricity tolerance zone is: Two coaxial cylinders.

## Related pages

- Previous control: [Circularity](https://shopmath.org/gdt/circularity.md) (○)
- Next control: [Profile of a Line](https://shopmath.org/gdt/profile-of-a-line.md) (⌒)
- All symbols: [GD&T symbol reference](https://shopmath.org/gdt.md)
- Tolerances: [ISO 286 fit reference](https://shopmath.org/fits.md)

---

*Source: [ShopMath](https://shopmath.org/gdt/cylindricity) — data verified August 1, 2026. Reference data; verify against the governing standard before manufacture.*