3-4-5 Square Checker
Check a layout corner for square using diagonal measurement.
Any multiple works: 3-4-5, 6-8-10, 9-12-15 — bigger triangles catch smaller angular errors. For full rectangles, equal diagonals is the final word.
Formula
3-4-5 Square Checker is a free 3 4 5 method for surveyors, civil engineers and property buyers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About 3-4-5 Square Checker
Check a layout corner for square using diagonal measurement. The calculation implements d = √(a² + b²); Pythagoras as a site tool (Pythagoras; setting-out practice). Any multiple works: 3-4-5, 6-8-10, 9-12-15 — bigger triangles catch smaller angular errors. For full rectangles, equal diagonals is the final word.
How to use 3-4-5 Square Checker
- 1Enter Side 1 measured in m.
- 2Enter Side 2 measured in m.
- 3Enter Diagonal as measured in m.
- 4Read True (square) diagonal, Out-of-square error instantly — no submit button needed.
- 5Need US units? Flip the SI/Imperial toggle and every field converts.
Why use 3-4-5 Square Checker?
- ✓Implements the standard formula — d = √(a² + b²); Pythagoras as a site tool
- ✓Reference cited on-page: Pythagoras; setting-out practice
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Built-in engineering verdict flags out-of-range results instantly
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the 3-4-5 Square Checker use?+
It computes d = √(a² + b²); Pythagoras as a site tool, per Pythagoras; setting-out practice. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Any multiple works: 3-4-5, 6-8-10, 9-12-15 — bigger triangles catch smaller angular errors. For full rectangles, equal diagonals is the final word.
Are regional land units exact?+
Conversion factors follow state revenue-department values noted on the tool. Units like bigha and katha vary by region, so always confirm the local factor named in your land records.
Is the 3-4-5 Square Checker free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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