Rectangle Area Calculator
Compute rectangle area and perimeter from length and width — flooring, paint, fencing estimates. A 12×15 ft room needs 180 sq ft of flooring — free, runs locally.
How to Use the Rectangle Area Calculator
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Frequently Asked Questions
How much flooring for a 12×15 room?
180 sq ft (12×15) — add 10% waste for cuts: order 198 sq ft. The tool shows area with perimeter for baseboard math in the same pass.
Area vs perimeter — which do I need?
Area for covering (paint, tile, sod); perimeter for edging (fencing, trim). Both display together so one entry serves both errands.
What units come out?
Square units of whatever you entered — feet in, square feet out. Keep both inputs in the same unit; mixing feet and inches silently corrupts the result.
Do my room dimensions leave the browser?
No — math runs locally in your browser. Dimensions never leave your device.
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Last updated October 2026