GD&T Symbol Guide
Square
Indicates a square feature so one size dimension controls both equal sides.
Definition
The square symbol states that the dimension applies to a square feature with equal side lengths.
It avoids repeating the same size requirement on both sides of the feature.
Application
Place the square symbol before the size dimension of the square feature.
Use it when the feature's two perpendicular sides share the same size and tolerance.
Square Drawing Use
Square is read with the adjacent dimension, note, or feature control frame so inspection uses the intended feature definition.
3D Tolerance Zone
This symbol defines or modifies a size, shape, or manufacturing dimension rather than creating a GD&T tolerance zone by itself.
Inspection Method
Read the symbol with the attached dimension, note, or feature control frame before evaluating the feature.
Verify the controlled feature using the drawing's stated limits, datum setup, and any special notes tied to the symbol.
Worked Read: Square
A drawing includes the Square symbol with a related feature requirement.
Identify
□
Recognize the Square symbol and the feature it modifies.
Read
Adjacent value
Use the attached dimension, note, or frame cells as the controlling requirement.
Inspect
Per drawing
Measure the named feature using the specified interpretation rather than assuming a generic size check.
Square clarifies how the feature is defined so the drawing and inspection method stay aligned.
Comparison Table
| Item | Controls | Typical Placement |
|---|---|---|
| Square | Dimension interpretation | Next to a dimension, note, or frame |
| GD&T control | Geometric variation | Feature control frame |
| Datum reference | Measurement setup | Datum feature or frame cell |
Notes
This page is part of the drawing-symbol reference set rather than a standalone geometric tolerance category.
When the symbol modifies a feature control frame, read it together with the tolerance value and datum references.