Arc Length

Indicates a dimension value is measured along a curved outline rather than as a chord.

⌒

6.000

The arc length symbol is placed over a value to show the dimension follows the length of an arc.

By default in ASME usage, the arc length applies to the surface nearest the dimension unless otherwise specified.

Use it for bent pipe, curved profiles, and partial circular outlines where path length matters.

Specify centerline arc length when the dimension is intended along the centerline rather than the nearest surface.

Arc Length Drawing Use

Arc Length is read with the adjacent dimension, note, or feature control frame so inspection uses the intended feature definition.

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0.04

This symbol defines or modifies a size, shape, or manufacturing dimension rather than creating a GD&T tolerance zone by itself.

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.

A drawing includes the Arc Length symbol with a related feature requirement.

Identify

⌒

Recognize the Arc Length 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.

Arc Length clarifies how the feature is defined so the drawing and inspection method stay aligned.

Item	Controls	Typical Placement
Arc Length	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

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.