A 12 × 12 ft room with 8 ft walls takes 12 sheets of 4 × 8 drywall for the walls and 5 for the ceiling: 17 sheets in total. That includes one door and one window subtracted and 10% added for cutting waste. With 4 × 12 sheets it’s 12.
The calculation
- Wall area: 4 walls × 12 ft × 8 ft = 384 sq ft.
- Subtract openings: a door (about 21 sq ft) and a window (about 15 sq ft) leave 348 sq ft.
- Add 10% waste: 348 × 1.10 = 382.8 sq ft.
- Divide by the sheet: a 4 × 8 sheet is 32 sq ft. 382.8 ÷ 32 = 11.96 → 12 sheets.
- Ceiling: 144 sq ft × 1.10 ÷ 32 = 4.95 → 5 sheets.
Check it sheet by sheet
The area method is quick, but drywall gets hung in whole sheets, so it’s worth checking against a layout. Sheets are usually hung horizontally, two rows high on an 8 ft wall:
- Each 12 ft wall is 1 1/2 sheets long and 2 sheets high: 3 sheets of 4 × 8 per wall, or exactly 2 sheets of 4 × 12.
- Four walls: 12 sheets of 4 × 8, or 8 sheets of 4 × 12, before any openings.
- Ceiling: 12 × 12 ft is 4.5 sheets of 4 × 8, so 5 sheets, or 3 sheets of 4 × 12.
The layout gives 12 + 5 = 17 sheets of 4 × 8, the same as the area method. In the layout, full sheets run right over the door and window and the openings are cut out afterward; those cutouts are the waste the 10% allowance pays for. That’s why the area method subtracts openings and still adds 10%.
Sheets by wall height and sheet size
12 × 12 ft room, one door, one window, 10% waste:
| Room | Area (sq ft) | 4 × 8 | 4 × 10 | 4 × 12 |
|---|---|---|---|---|
| 8 ft walls, no ceiling | 348 | 12 | 10 | 8 |
| 8 ft walls + ceiling | 492 | 17 | 14 | 12 |
| 9 ft walls, no ceiling | 396 | 14 | 11 | 10 |
| 9 ft walls + ceiling | 540 | 19 | 15 | 14 |
| 10 ft walls + ceiling | 588 | 21 | 17 | 15 |
For other room sizes, the drywall calculator counts sheets, screws, joint compound and tape.
Wall height changes the best sheet
With 9 ft walls, two rows of 4 ft sheets leave a 1 ft gap. You can fill it with strips, but that adds a seam the full length of the wall. Two better options: hang 4 × 9 or 4 × 10 sheets vertically, or use 54 in wide board, which is made for 9 ft walls hung horizontally in two rows. With 10 ft walls, vertical 4 × 10s avoid a third row.
The rest of the shopping list
For the 8 ft room with the ceiling, 17 sheets of 4 × 8:
- Screws: about 28 per wall sheet and 35 per ceiling sheet, so roughly 511. 1 1/4 in coarse-thread screws suit 1/2 in board on wood studs.
- Joint compound: about 4.9 gallons, so 2 pails of premixed all-purpose compound.
- Paper tape: about 201 ft, one 500 ft roll, plus metal or paper-faced corner bead for outside corners.
Ceiling board is different
Many builders use 1/2 in sag-resistant board or 5/8 in board on ceilings, especially with joists 24 in apart. Regular 1/2 in board can sag between framing members over time. Check what your framing and local code call for before buying the ceiling sheets with the wall sheets.