Squaring Tool: Diagonal Check

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About this app

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.
Check if walls, decks & foundations are square. Diagonal measurement tool.
Updated on
Aug 11, 2026

Data safety

Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.
  • No data shared with third parties
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  • No data collected
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What’s new

v1.1: Android 16 compatibility and technical update