DIY Home CalcsDrywall Calculator
Calculate how many sheets of drywall (gypsum board) you need to hang a room. Enter the room size and openings, choose 4 × 8 or 4 × 12 sheets, and optionally include the ceiling.
How the drywall calculation works
The calculator finds the wall area from the room's perimeter and height, subtracts 20 sq ft per door and 15 sq ft per window, adds the ceiling if selected, then adds the waste allowance and divides by the area of one sheet.
Worked example
A 12 × 12 ft room with 8 ft walls, one door and one window, using 4 × 8 sheets:
- Wall area: 48 ft perimeter × 8 ft = 384 sq ft.
- Minus openings: 384 − 35 = 349 sq ft.
- Plus 10% waste: 383.9 sq ft.
- Sheets: 383.9 ÷ 32 = 12.0, so buy 12 sheets, or 13 for a spare.
Hanging sheets horizontally on 8 ft walls means exactly two rows per wall, which keeps the seam at a comfortable height to tape.
Other materials for a drywall job
| Material | Rule of thumb (estimate) |
|---|---|
| Drywall screws | About 32 per 4 × 8 sheet on walls at 16 in stud spacing |
| Joint tape | Measure the total length of all seams and inside corners, then add about 10% |
| Joint compound | Varies with finish level; a 4.5 gal bucket of premixed all-purpose compound is a common starting point for one average room |
| Corner bead | One length per outside corner, measured to height |
These are common trade estimates, not manufacturer specifications. Coverage varies with finish level and technique.
Tips
- Use moisture-resistant board in bathrooms and cement board behind tile in showers.
- Stagger the vertical seams between rows so they don't line up.
- Once the walls are finished, the paint calculator will tell you how much primer and paint you need.
Frequently asked questions
How many sheets of drywall do I need for a 12x12 room?
With 8 ft walls, a 12 × 12 room has 384 sq ft of wall. That is 12 sheets of 4 × 8 drywall before waste, or 14 with a 10% allowance. The ceiling adds 144 sq ft, about 5 more sheets.
Should I use 4x8 or 4x12 sheets?
4 × 12 sheets mean fewer seams to tape, which saves finishing time, but they are heavy (around 80 lb for 1/2 in) and hard to carry up stairs. 4 × 8 sheets are easier to handle alone and fit in more vehicles.
Do I subtract doors and windows from drywall?
For an estimate, yes, but many pros subtract only large openings. Offcuts from around doors and windows rarely fit elsewhere, so the waste allowance covers them.
How many screws per sheet of drywall?
A common rule of thumb is about 32 screws for a 4 × 8 sheet on walls with studs at 16 in centers, more on ceilings. One pound of 1-1/4 in coarse-thread screws is roughly 300 screws, but count varies by brand.
What thickness of drywall should I use?
1/2 in is standard for interior walls. 5/8 in is common for ceilings to reduce sag and is required as fire-rated (Type X) in many places, such as walls between a house and an attached garage. Check local code.