How to use this calculator
- Enter the room length, width and wall height.
- Choose whether to include the ceiling.
- Enter the total area of doors and windows to subtract.
- Pick your sheet size. Longer sheets mean fewer joints to tape.
- Add 10–15% waste for cut-outs and offcuts.
How drywall quantities are calculated
The wall area is the room's perimeter × wall height, minus openings, plus the ceiling if included. Dividing that by the area of one sheet and adding waste gives the sheets to buy.
Fasteners, compound and tape are estimated from industry averages: about 32 screws per sheet, roughly 9.4 gallons of ready-mixed compound and 370 ft of tape per 1,000 sq ft of board.
Pro tips
- Use moisture-resistant board in bathrooms and fire-rated (Type X) board where code requires it, such as garage walls next to living space.
- Hang ceilings first, then walls, with the top wall sheet pushed up tight against the ceiling.
- Stagger the joints so they don't line up with the corners of doors and windows. This reduces cracking.
Frequently asked questions
How many sheets of drywall do I need for a 12×12 room?
A 12 × 12 ft room with 8 ft walls has 384 sq ft of wall area and 144 sq ft of ceiling. With one door and one window and 10% waste, that's about 17 sheets of 4×8 drywall including the ceiling.
What thickness of drywall should I use?
½″ (12.5 mm) is standard for walls. Use ⅝″ (15 mm) for ceilings with wide joist spacing, fire-rated assemblies and better sound control.
How many screws per sheet of drywall?
About 28–32 screws for a 4×8 sheet on walls with studs 16″ apart. Ceilings need slightly more, with screws every 12″ along each joist.
These results are estimates for planning and budgeting. Actual quantities depend on site conditions, products and workmanship. Check structural and code requirements with a licensed professional before you build.