How to calculate drywall for a room
Add up the area of every wall, add the ceiling if you're covering it, subtract the large openings, and divide by the area of one sheet. Then add some extra for cuts and broken corners.
Wall area = 2 × (length + width) × wall height
Sheets = (wall area + ceiling area − openings) ÷ sheet area × (1 + waste %)
Example: a 12 × 12 ft room with 8 ft walls has 2 × 24 × 8 = 384 sq ft of wall. Subtract one door (21 sq ft) and one window (15 sq ft) and you're at 348 sq ft. That's 10.9 sheets of 4 × 8, or 12 sheets with 10% extra.
Drywall sheet sizes
| Sheet | Area | Good for |
|---|---|---|
| 4 × 8 ft | 32 sq ft | Most DIY jobs; easy to carry and fit through doors |
| 4 × 10 ft | 40 sq ft | 9 ft walls hung vertically; fewer seams |
| 4 × 12 ft | 48 sq ft | Long walls and ceilings; fewest seams, two-person lift |
Finishing supplies (rough guide)
These are planning estimates. How much mud you use depends on your skill, the number of coats and the level of finish.
- Screws: about 1 per square foot, or roughly 32 per 4 × 8 sheet.
- Joint compound: about one 4.5 gallon bucket per 500 sq ft.
- Paper tape: about 370 ft per 1,000 sq ft. Tape is usually sold in 250 or 500 ft rolls.
- Corner bead: measure each outside corner's height separately.
Hanging tips
- Hang the ceiling first, then the walls, so wall sheets help support the ceiling edges.
- On walls, hanging sheets horizontally usually means fewer and easier-to-finish seams.
- Stagger end joints so they don't line up from row to row, and keep them off the edges of doors and windows to reduce cracking.
Frequently asked questions
How many sheets of drywall do I need for a 12x12 room?
With 8 foot walls, a 12 × 12 room has 384 square feet of wall. That's 12 sheets of 4 × 8 drywall, or 14 with 10% waste (rounded up). Add 5 more sheets if you're also doing the 144 square foot ceiling.
Should I subtract doors and windows?
Yes for large openings, which is why the calculator subtracts a standard door (about 21 sq ft) and window (about 15 sq ft). Many installers hang sheets right over small openings and cut them out afterward, so the waste allowance covers those offcuts.
What size drywall sheets should I use?
4 × 8 sheets are the easiest to carry and fit most cars and stairways. Longer 4 × 10 and 4 × 12 sheets mean fewer seams to tape and finish, which saves time on walls and ceilings if you can get them into the room.
What thickness of drywall do I need?
1/2 inch is standard for interior walls. 5/8 inch is common for ceilings, because it sags less, and is required for fire-rated walls, such as between a garage and the house in many codes.
How much joint compound and tape do I need?
As a rough guide, plan on about one 4.5 gallon bucket of premixed joint compound per 500 square feet of drywall and about 370 feet of tape per 1,000 square feet. Actual use depends on how many coats you apply and how smooth you finish.