Area Calculator — Square Feet, Shapes, Rooms & Land
Calculate square footage for shapes, rooms, walls, roofs, and irregular land; include cutouts, waste, packages, cost, formulas, and diagrams.
Calculate area and perimeter for a shape
Choose one of ten shapes, enter dimensions in any supported length unit, and convert the area instantly.
Total square footage for rooms and project sections
Add measured sections, subtract stairs or cutouts, then include material overage, package coverage, and price.
Calculate interior wall surface area
Use room perimeter and height, subtract the combined door and window opening area, then add an optional overage.
Estimate sloped roof surface area
Start with the horizontal footprint, add equal eave overhang, and apply a rise-per-12 pitch factor plus waste.
Area of an irregular polygon from coordinates
Enter boundary points in order around a floor, lot, or drawing. The shoelace formula calculates area, perimeter, centroid, and orientation.
Shape diagram
Calculation
Area details
Square footage calculator for rooms
Add every rectangular room or section, repeat identical spaces with quantity, and subtract cutouts. The project result can include flooring or tile waste, package rounding, and estimated package cost.
Area calculator for common shapes
Calculate rectangles, squares, circles, right triangles, trapezoids, parallelograms, ellipses, sectors, annuli, and regular polygons with perimeter and unit conversions.
Wall and roof area calculators
Wall mode uses room perimeter × height minus door and window openings. Roof mode converts a horizontal footprint to sloped surface area with a rise-per-12 factor and optional overhang.
Land and irregular polygon area
Coordinate mode applies the shoelace formula to three through twenty boundary points. It also reports perimeter, centroid, orientation, square feet, acres, and hectares.
Frequently asked questions
How do I calculate square footage?
Measure length and width in feet and multiply them. For several rooms, calculate each rectangle and add the results; subtract permanent cutouts if they will not receive material.
How much flooring waste should I add?
Simple straight installations often use 5% to 10%, while diagonal layouts, irregular rooms, and pattern matching may need more. Follow the product and installer guidance.
What is a roofing square?
One roofing square equals 100 square feet of roof surface. The calculator reports squares after pitch, overhang, and waste are applied.
Do coordinate points need to close the polygon?
No. Enter each corner once in clockwise or counterclockwise order; the calculator automatically connects the final point back to the first.
Measurement notes
Results are mathematical estimates. Confirm dimensions on site, keep units consistent, and follow product coverage, local building, surveying, and installation requirements before purchasing materials.
