How to estimate drywall
Add the wall area (perimeter × height) and the ceiling if needed, subtract doors and windows, add waste for cuts, and divide by the sheet size. Longer sheets mean fewer joints to tape.
Walls = 2 × (Length + Width) × Height
Area = Walls + Ceiling − Openings
Sheets = Area × (1 + Waste) ÷ Sheet area
Example: 12 × 12 ft room, 8 ft walls, with ceiling
384 sq ft of wall + 144 ceiling − 36 openings = 492 sq ft. With 10% waste: 541 sq ft ÷ 32 = 17 sheets of 4 × 8.
Which thickness?
- 1/2 in: standard for walls
- 5/8 in Type X: fire-rated, required on garage walls shared with the house and often on ceilings
- Moisture-resistant: bathrooms and laundry rooms
Frequently asked questions
How many sheets of drywall for a 12x12 room?
About 12–13 sheets of 4 × 8 for the walls alone, or 17 including the ceiling.
How many screws per sheet of drywall?
About 28–32 for a 4 × 8 sheet on walls with studs 16 in on center.
Should I hang drywall horizontally?
Usually yes on walls. It reduces joint length and puts seams at a comfortable working height.