About Arch Calculator
Arch Calculator was created to bridge the gap between pure architectural geometry and real-world jobsite execution.
Our Core Mission
Eliminate costly layout mistakes, bowed trim, and unstable masonry arches by providing finish carpenters, drywall installers, bricklayers, and architects with instant, mathematically verified layout coordinates, fractional dimensions, and voussoir calculations.
Mathematical Rigor & Engineering Models
Unlike generic chord calculators, Arch Calculator models seven distinct geometric arch classifications:
- Segmental Arches: Computed via the Intersecting Chords Theorem with continuous sagitta curves.
- Elliptical Arches: Scribed using true semi-major and semi-minor focal point distances (c = √(a² - b²)) and Ramanujan perimeter approximations.
- Gothic & Pointed Arches: Dual-arc equilateral and lancet intersections.
- Masonry Voussoirs: Strict adherence to odd-integer brick count laws ensuring a central apex keystone and calculated skewback seating angles.
Editorial & Trade Standards
Every equation, layout method, and coordinate stepping formula published on this website is derived from classical analytic geometry, ASTM building material standards, and International Residential Code (IRC) framing guidelines. We aim to provide field-ready dimensions down to 1/16" carpenter fractions and millimeter precision.
Read our complete Editorial & Verification Policy to learn how formulas are tested and how to report any calculation discrepancies.
Project Maintainers & Transparency
Arch Calculator is an independent technical toolset maintained by a collaborative group of software developers and carpentry enthusiasts. Our tools execute 100% locally in your browser with zero tracking of user project dimensions.
Because physical structural projects carry inherent safety requirements, our calculators are provided for preliminary sizing, layout templating, and educational reference. We actively invite feedback and peer review from licensed Professional Engineers (PE), registered architects, and master craftspeople.