How to estimate drywall
Measure the wall area, subtract doors and windows, and divide by the area of one sheet. A 4 × 8 ft sheet covers 32 sq ft, a 1200 × 2600 mm board 3.1 m². Longer sheets mean fewer joints to tape, if you can get them into the room.
Screws, tape and compound
Walls take roughly one screw per square foot with studs at 16 in (40 cm). Joint tape and compound depend on the number of joints. The estimates here assume standard taped joints with three coats of compound.