Arc & Arch Layout Calculator

Arc & Arch Layout Calculator is the precision toolkit every carpenter, joiner, mason, stonemason, builder and DIY enthusiast needs to lay out perfect arches and curves on any job — without complex trigonometry and without ever pulling string from a nail.

TWO PROFESSIONAL CALCULATORS IN ONE APP

Large Arc Layout
Set out a large-radius arc inside any confined space — an opening, a wall, a panel or a curved trim run. Enter the chord width plus either the rise (height) or radius and instantly see:
• Sweep angle, arc length, slice and full-circle area
• Inside arc mark-out — heights every increment from chord centre out
• Outside arc mark-out with optional outer offset
• An interactive set-out diagram you can pinch to zoom and drag to pan
• A printable template with automatic A4, Letter, A3, A2 and A1 page-fit guidance
• A bonus calculator that derives width, height, length and area from radius and sweep angle

Gothic Arch Layout
Design true masonry arches with mathematical precision. Choose equilateral, lancet or drop arches — the app classifies them automatically — and instantly receive every dimension you need:
• Inner and outer radius, inner and outer height
• Triangle chord and triangle drop for the gothic set-out
• Intrados and extrados arc lengths
• Setout mark-out heights from centre out
• Voussoirs: full unit count per side, inner and outer arc per voussoir, plus a dedicated keystone diagram
• Optional full-scale keystone and voussoir templates ready to print

EVERY MEASUREMENT, METRIC OR IMPERIAL
Every input switches instantly between Metric (mm) and Imperial (feet, inches and 1/16 to 15/16 fractions). Imperial inputs use clean three-wheel pickers — feet, inches, fraction — so a 6 ft 3 1/2 in chord takes seconds.

INTERACTIVE DIAGRAMS YOU CAN ACTUALLY READ
Every calculation is paired with a crisp, vector-quality diagram. Pinch to zoom, drag to pan, double-tap to fit, and use the live measure tool to read distances off the drawing.

EXPORT TO PDF FOR THE WORKSHOP
One tap exports a complete multi-page PDF: a tidy summary page with all your inputs and results, followed by every diagram on its own page — perfect for printing the template at full scale or sharing with the team.

NATIVE iOS DESIGN
• Built with SwiftUI for iPhone and iPad
• Works completely offline
• Saves your last inputs automatically
• No accounts, no subscriptions, no ads
• Respects Dynamic Type and Dark Mode

Stop guessing. Calculate, lay out, print and build — accurately, every time.