About this focused free tool

Describe a curve.
Keep the method visible.

Arcspan reconstructs one ideal minor circular centreline from a chord and perpendicular midpoint rise. Its purpose is transparent craft, paper-template and drawing geometry.

One calculator, bounded assumptions

The calculator provides the circle radius and centre offset, angle, arc length, equal chord-station coordinates and a calibrated SVG. Zero rise has an explicit straight-line result. The original worked guide explains the formulas, units, shallow-curve arithmetic and approximation limits.

It does not fit an ellipse or irregular object, calculate structural spans or loads, determine safe bending or material behaviour, verify compliance, or add kerf and thickness allowances. Its name describes geometric layout; it makes no building-design claim.

Free and local

Cloudflare Web Analytics is enabled in this site's hosting settings for aggregate traffic and page-performance reports when its beacon loads. Read Privacy for measurement and hosting details. The calculator remains free. Publisher identification does not itself activate advertising or establish approval or earnings; the site's actual advertising configuration is described in the privacy notice.

Shared portfolio contact

Arcspan is part of the independent free-tool portfolio that includes Yardfill. The existing shared public forwarding alias is transparently reused rather than presented as a new Arcspan mailbox. Read Privacy for local input, ordinary hosting and email handling.