Guide
How Many Sheets of Drywall Do I Need?
Add wall and ceiling area, add 10–15% waste, and divide by the sheet size: 32 sq ft for 4x8, 48 for 4x12. Worked example for a room and a house.
Updated · FloorFigures
Short answer
Add the wall area (perimeter × ceiling height, less doors and windows) and the ceiling area, add 10–15% for waste, and divide by the sheet size: 32 sq ft for a 4×8 sheet, 40 for 4×10, 48 for 4×12. A 12' × 14' room with 8 ft walls, a door and a window is 380 + 168 = 548 sq ft; with 10% waste that's 602.8 sq ft, or 19 sheets of 4×8.
Drywall is bought by the sheet, and the sheet count comes straight from the room sizes. Here's how to work it out for one room or a whole house, what to do about doors and windows, and how much extra to buy.
- 1
Work out the wall area
Perimeter × ceiling height for each room. A 12' × 14' room has 52 ft of wall; at 8 ft that's 416 sq ft. - 2
Take off the openings
Subtract doors (about 21 sq ft each) and windows (about 15 sq ft each), unless you'll hang over the windows. - 3
Add the ceiling
A flat ceiling is length × width: 12 × 14 = 168 sq ft. - 4
Add waste, divide by the sheet size and round up
548 × 1.10 = 602.8 sq ft. 602.8 ÷ 32 = 18.8, so 19 sheets of 4×8.
What size are drywall sheets?
Panels are 48 inches (4 ft) wide, and USG's regular lengths run from 8 to 14 ft. USG also makes 54-inch-wide panels in 1/2-inch and 5/8-inch thicknesses: two of them stacked horizontally cover 108 inches, a 9 ft wall.
| Sheet | Area | Sheets for 1,000 sq ft (with 10% waste) |
|---|---|---|
| 4×8 | 32 sq ft | 35 |
| 4×10 | 40 sq ft | 28 |
| 4×12 | 48 sq ft | 23 |
| 4×14 | 56 sq ft | 20 |
Longer sheets mean fewer end joints to tape, but they're heavier and harder to get into a house. Matching sheet length to wall length helps: a 12 ft wall takes 12 ft sheets with no end joint and almost no offcut.
How do I calculate drywall for walls and ceilings?
For each room, walls = perimeter × ceiling height, and a flat ceiling = length × width. Add the rooms together. Working room by room counts both faces of every interior wall, which is right, because each face gets its own sheet. Exterior walls only get drywall on the inside face, and room-by-room measuring counts them once.
A sloped or vaulted ceiling has more surface than the floor under it, so measure along the slope. Closets count too: measure each as its own small room.
Should I subtract doors and windows?
Usually yes for doors: they're full-height gaps with no board in them. For windows, estimators differ. Some deduct every window; others deduct only large ones, because the board is often hung straight over a window and the opening cut out afterward, so the cutout ends up as scrap rather than a saving. Either way works if the waste allowance matches: if you hang over windows, leave them in the area or use the high end of the waste range. When you only have counts, 21 sq ft per door (3' × 7') and 15 sq ft per window (3' × 5') are the allowances our calculators use.
How much waste should I add for drywall?
A 10–15% allowance is common. Stay near 10% for simple rectangular rooms with sheet lengths that suit the walls. Go toward 15% for many corners and short walls, angled ceilings, small rooms and stairwells, or when you hang over openings and cut them out. Rounding up to whole sheets adds a little on top.
Which way should drywall be hung?
On walls, sheets are commonly hung horizontally: two 4 ft sheets stack to exactly 8 ft, the long seam lands at a comfortable working height, and long sheets cut down the number of end joints. Ceilings are usually hung before walls. Direction doesn't change the area math, but it does change which sheet length wastes the least.
Example: drywall for one room
A 12' × 14' bedroom with 8 ft walls, one door and one window, ceiling included:
| Step | Math | Result |
|---|---|---|
| Walls, gross | 2 × (12 + 14) × 8 = 52 × 8 | 416 sq ft |
| Less door and window | 416 − 21 − 15 | 380 sq ft |
| Ceiling | 12 × 14 | 168 sq ft |
| Total | 380 + 168 | 548 sq ft |
| Add 10% waste | 548 × 1.10 | 602.8 sq ft |
| 4×8 sheets | 602.8 ÷ 32 = 18.8, rounded up | 19 sheets |
| 4×10 sheets | 602.8 ÷ 40 = 15.1, rounded up | 16 sheets |
| 4×12 sheets | 602.8 ÷ 48 = 12.6, rounded up | 13 sheets |
At 15% waste the total is 630.2 sq ft: 20 sheets of 4×8, 16 of 4×10 or 14 of 4×12.
Example: drywall for a whole house
A small single-story house with six rooms and 8 ft ceilings, doors at 21 sq ft and windows at 15 sq ft:
| Room | Size | Doors / windows | Walls, net | Ceiling | Total |
|---|---|---|---|---|---|
| Living room | 16' × 14' | 2 / 2 | 408 sq ft | 224 sq ft | 632 sq ft |
| Kitchen | 12' × 10' | 1 / 1 | 316 sq ft | 120 sq ft | 436 sq ft |
| Bedroom 1 | 12' × 12' | 2 / 2 | 312 sq ft | 144 sq ft | 456 sq ft |
| Bedroom 2 | 11' × 10' | 2 / 1 | 279 sq ft | 110 sq ft | 389 sq ft |
| Bathroom | 8' × 5' | 1 / 1 | 172 sq ft | 40 sq ft | 212 sq ft |
| Hall | 10' × 3' 6" | 4 / 0 | 132 sq ft | 35 sq ft | 167 sq ft |
| Total | 12 / 7 | 1,619 sq ft | 673 sq ft | 2,292 sq ft |
| Waste | Area to cover | 4×8 sheets | 4×12 sheets |
|---|---|---|---|
| 10% | 2,521.2 sq ft | 78.8 → 79 | 52.5 → 53 |
| 15% | 2,635.8 sq ft | 82.4 → 83 | 54.9 → 55 |
If you'll hang over the seven windows instead, add their 105 sq ft back: 2,397 sq ft, or 83 sheets of 4×8 at 10% waste. A real house adds closets, stairwells and a garage if it's being finished. Some walls and ceilings, such as those shared with a garage, may call for a specific type of board under your local code, so check before you order.
A drywall takeoff from plans in FloorFigures
If you have the floor plan, open it in FloorFigures: it's free and runs in your browser. On a PDF it sets the scale from the printed dimensions, and pressing A finds every room. Set each room's ceiling height (8 ft by default) and the area of its openings, and the Takeoff tab gives drywall sheets per room from walls less openings plus ceiling, with your waste allowance (10% by default) and sheet size (4×8 by default; change it to 48 sq ft for 4×12). The same takeoff gives paint gallons, and a full material takeoff walks through the rest.
Questions
- How many sheets of drywall do I need for a 12x12 room?
- With 8 ft walls, one door and one window, a 12x12 room has 348 sq ft of wall after openings and 144 sq ft of ceiling, 492 sq ft in all. Add 10% waste and you need 541.2 sq ft: 17 sheets of 4x8 or 12 sheets of 4x12. Walls only, it's 382.8 sq ft, or 12 sheets of 4x8.
- How many square feet is a sheet of drywall?
- Drywall panels are 4 ft wide, so a 4x8 sheet is 32 sq ft, a 4x10 is 40 sq ft, a 4x12 is 48 sq ft and a 4x14 is 56 sq ft. USG also makes 54-inch-wide panels in 1/2-inch and 5/8-inch thicknesses.
- How much extra drywall should I buy?
- A waste allowance of 10–15% is common. Use the low end for simple rectangular rooms where sheet lengths match the walls, and the high end for rooms with many corners, short walls, angled ceilings, or windows the board is hung over and cut out.
- Do you subtract windows and doors when estimating drywall?
- Usually yes for doors, which are full-height gaps in the wall. For windows, estimators differ: some deduct them and some deduct only large ones, because the board is often hung over a window and the cutout becomes scrap. If you hang over windows, leave them in the area or raise the waste allowance.
- How do I estimate drywall for a whole house?
- Work room by room: wall area (perimeter × ceiling height, less doors and windows) plus ceiling area (length × width) for each room. Add them up, add 10–15% waste and divide by the sheet size. Measuring room by room counts both faces of interior walls, which is correct, since each face gets its own drywall.