> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/templates/cadd/dimensionarclength-cadd.md).

# Arc Length Dimension

An **Arc Length Dimension** measures the length along a curved edge — the actual curved distance, not the chord between endpoints. In bridge drawings it's used for the arc length of curved parapets, curved deck edges over horizontal curves, transition arcs, and any place where the curved distance is what matters (for take-offs of curved railings, curb runs along curves, etc.).

Pick the arc, and the dimension shows the length along the curve.

## Text and units

**Label:** Override text. Leave blank to use the auto-computed arc length.

**Prefix:** Text before the value. Default `⌢` (arc-length symbol).

**Suffix:** Text after the value.

**Precision:** Number of decimal places.

**Unit Style / Length Unit:** Units.

## Typography

**Text Height:** Text size in real units.

**Font Family / Font Weight / Font Style:** Font controls.

## Notes

If the arc is shallow enough that the chord and the arc length are nearly equal, a Linear Dimension across the chord is often clearer than an Arc Length Dimension along the curve. Reserve arc-length callouts for curves where the difference between chord and arc matters (long, sharp curves; transition spirals; curved railing runs at small radii).


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