Walls and ceilings

Drywall Calculator

Estimate full sheets from total surface area, sheet size, and a cutting allowance. Enter the job dimensions below, then review the guide before ordering.

Drywall calculation formula

surface area / sheet area x (1 + waste percentage) = sheets

Worked example: An 800 sq ft surface divided by a 32 sq ft sheet equals 25 sheets. With 10% waste, the result is 27.5, so purchase 28 sheets.

Measure the covered surface

Add wall and ceiling areas that will receive drywall. Whether to subtract openings depends on layout: door and window cutoffs sometimes become useful pieces elsewhere, but small openings rarely reduce the number of full sheets purchased.

Selecting sheet length

Longer sheets can reduce butt joints but are heavier and need room for delivery and handling. Choose a length that matches framing layout, ceiling height, crew capacity, and access through the building.

Waste and layout

Simple rooms may need about 10% extra. Angled ceilings, many openings, small rooms, and decorative details create more offcuts. Fire-rated and moisture-resistant boards should be counted separately from standard board.

Before placing an order

Recheck field measurements, confirm the selected product's actual package coverage or density, and ask the supplier about order increments, minimum quantities, delivery limits, and return rules. Keep unlike products and assemblies in separate calculations.