Calculator · Geometry & layout
Diagonal & Squareness Calculator
The free Diagonal & Squareness Calculator answers one question: Check a carcass or frame for square. Enter your numbers in inches or millimeters and the result updates instantly in your browser, with no sign-up and no app to install. Use it on your phone at the bench, then copy or print the result for your cut list.
Measure corner to corner both ways: if both diagonals match this number, the frame is square.
Which other geometry & layout calculators help with this project?
- Polygon Side Length Calculator — Side length for hexagons, octagons and more.
- Hexagon Calculator — Across flats, across corners and area from side length.
- Circle Calculator — Circumference and area for round tabletops.
- Golden Ratio Calculator — Pleasing proportions for furniture design.
What you'll need for this project
Tools
Screws & hardware
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Build it · Beginner · 2 hours
Download the complete plan with cut list and materials list (PDF)
Assembly Squares & Clamping Jig — Four 90° corner squares that hold cabinets dead-square during glue-up. Drawings, cut list with board-foot totals, hardware list and step-by-step instructions.