Squaring Tool: Diagonal Check

Is your structure actually square?

Two diagonal measurements tell you the truth. If they match, your
corners are at 90 degrees. If they don't, something needs to move -
and this app tells you exactly which corner, and by how much.

HOW IT WORKS
Enter the two side lengths and the two diagonals. The app compares
them against the Pythagorean theorem and shows a live diagram of
your structure. An animated arrow points to the corner that's off
and gives you the correction distance.

No trigonometry. No 3-4-5 triangle guesswork. No second person
holding the tape.

BUILT FOR
- Deck and patio layout
- Foundation and footing checks
- Shed and garage framing
- Wall framing and partition walls
- Fence lines and posts
- Concrete formwork
- Tiling and flooring layout

WHY DIAGONALS
The 3-4-5 method only checks one corner at a time, and it fails on
structures where you can't reach a clean measurement. Diagonal
comparison checks the whole rectangle at once. It's how professionals
have squared buildings for centuries - this app just does the math
instantly and shows you the fix.

FEATURES
- Instant square / not-square verdict
- Visual diagram of your actual structure
- Animated correction arrow showing which corner to move
- Exact correction distance
- Works offline, on any job site
- Available in English, Finnish and Swedish

Free to use. Pro unlock available as a one-time purchase - no
subscription, no ads.

Measure twice. Build once.