Drywall quantity formula
The calculator adds wall area and the optional ceiling, subtracts measured openings, applies waste, and rounds up to whole sheets. The fastener and tape numbers are rough planning aids, not fastening-pattern instructions.
wall area = 2 × (length + width) × height
net board area = walls + ceiling − openings
sheets = ceil(net area × (1 + waste) ÷ sheet area)
Actual sheet orientation and seam layout can change the most efficient sheet size. Use the result as the purchase baseline, then lay out complicated walls separately.