A 12×12 room with 8 ft ceilings needs 19 sheets of 4×8 drywall for the walls and ceiling, or 14 sheets for the walls only (both include 10% extra for cuts and mistakes). Doors and windows lower that a little. Plug in your own room in the QtyLab drywall calculator.
The math for a 12×12 room
- Walls: 4 walls × 12 ft × 8 ft = 384 sq ft
- Ceiling: 12 × 12 = 144 sq ft
- Total: 528 sq ft
- Add 10% waste: 528 × 1.10 = 580.8 sq ft
- Divide by one 4×8 sheet (32 sq ft): 580.8 ÷ 32 = 18.2 → 19 sheets
Most 12×12 bedrooms have one door and one window. The calculator subtracts 20 sq ft for each door and 15 sq ft for each window, which brings a typical bedroom to 493 sq ft and 17 sheets with the ceiling, or 12 sheets for the walls only. See it with one door and one window.
12×12 room by ceiling height and sheet size
No doors or windows subtracted, 10% waste included.
| Ceiling height | Walls only (4×8) | Walls + ceiling (4×8) | Walls + ceiling (4×12) |
|---|---|---|---|
| 8 ft | 14 | 19 | 13 |
| 9 ft | 15 | 20 | 14 |
| 10 ft | 17 | 22 | 15 |
Bigger 4×12 sheets mean fewer seams to tape and mud, but they’re heavy (roughly 60–90 lb for a 1/2 inch sheet, depending on lightweight or standard board) and need two people and a way to get them into the room.
Other common room sizes (8 ft ceilings, 4×8 sheets)
Mistakes that throw the count off
- Over-subtracting openings. Cutting around a small window still uses most of a sheet. If you’re unsure, leave it in — one spare sheet is cheaper than a second trip.
- Skipping the waste factor. Cutouts for outlets, corners and a cracked sheet or two add up. 10% is a safe default; go 15% for rooms with lots of angles.
- Using wall board on the ceiling without checking. Many pros use 1/2 inch “ceiling board” (sag-resistant) or 5/8 inch overhead.
- Forgetting closets. Measure closet walls and ceilings separately and add them in.
What to buy for a 12×12 room
- 19 sheets of 4×8 drywall (1/2 inch for walls) — buy locally; most stores deliver
- Drywall screws (1-1/4 inch coarse thread for 1/2 inch board on wood studs): shop drywall screws
- Joint compound and paper tape: shop drywall tape
- Drywall T-square for straight cuts: shop drywall T-squares
- Drywall screw gun bit or setter so screws sink just right: shop screw setter bits
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More on sheet sizes, ceilings and mud: How many drywall sheets do I need? Painting the room after? The paint calculator gives gallons for the same walls.
FAQ
How many sheets of drywall for a 12×12 room?
With 8 ft ceilings: 19 sheets of 4×8 for walls and ceiling, or 14 for the walls only, including 10% extra.
How many square feet of drywall are in a 12×12 room?
384 sq ft of wall with 8 ft ceilings, plus 144 sq ft of ceiling, for 528 sq ft total.
Should I use 4×8 or 4×12 sheets?
4×12 sheets cut the number of seams (13 sheets instead of 19 for a 12×12 room with ceiling), but they’re harder to carry and lift. 4×8 is easier for one person.
Do I subtract doors and windows?
Yes. The QtyLab calculator subtracts 20 sq ft per door and 15 sq ft per window. A 12×12 room with one of each needs 17 sheets with the ceiling instead of 19, or 12 for the walls only.