Room Survey & True-Area Calculator

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Width, wall A m

Width, wall B (opposite) m

Depth m

Wall height m

Openings — doors and windows, total area m², 0 if none

Enter both wall widths, the depth and the wall height, then press Calculate.

From the book — Chapter 2. True floor = ½(width A + width B) × depth — the trapezium rule. Order floor = the larger width × depth, because you buy to the largest measurement. Diagonal = √(width² + depth²) from each end.

Matches Chapter 2's survey of the box room (3.60 / 3.64 / 2.70) exactly. Everything stays in your browser — no sign-up, nothing stored.