Find out how many sheets of drywall you need for a room. Enter the room size, choose whether to include the ceiling, subtract doors and windows, and pick a sheet size.
How to calculate drywall
- Wall area = perimeter × wall height. For a rectangular room, perimeter = 2 × (length + width).
- Ceiling area = length × width (optional).
- Subtract openings: a standard door is about 21 sq ft, a typical window about 15 sq ft.
- Add waste, usually 10–15%.
- Divide by the sheet area and round up: 4×8 = 32 sq ft, 4×10 = 40 sq ft, 4×12 = 48 sq ft.
Example
A 12 × 12 ft room with 8 ft walls: walls 48 × 8 = 384 sq ft, ceiling 144 sq ft, minus one door (21) and one window (15) = 492 sq ft. With 10% waste that is 541 sq ft, or 17 sheets of 4×8 drywall.
4×8 vs. 4×12 sheets
Larger 4×12 sheets mean fewer seams and less taping, but they are heavy and harder to carry and lift. 4×8 sheets are easier for one person and for ceilings.
Which thickness?
1/2-inch drywall is common for interior walls. 5/8-inch (often Type X, fire-rated) is used where codes require fire resistance, such as walls between a garage and the house, and on some ceilings. Check your local code.
Frequently asked questions
How many screws per sheet of drywall?
Roughly one screw per square foot is a common estimate, about 32 for a 4×8 sheet. Follow the manufacturer’s fastening schedule.
How many sheets of drywall for a 10×10 room?
Walls 40 × 8 = 320 sq ft plus a 100 sq ft ceiling = 420 sq ft, about 14 sheets of 4×8 before subtracting openings and adding waste.