How It Works
Wall area = perimeter × height. Add the ceiling if you're doing it. Subtract ~20 sq ft per door and ~15 sq ft per window, then add 10% waste for cuts.
Calculation Explanation
Example: 12×12 room (48-ft perimeter), 8-ft walls, 1 door, 1 window, with ceiling → 384 + 144 = 528 − 35 = 493 sq ft → 493 × 1.1 ≈ 543 → 17 sheets of 4×8.
After the boards go up, estimate how much paint you'll need to finish the room.
Drywall Sheets Quick Reference (4×8, incl. ceiling)
| Room | Wall + Ceiling Area | 4×8 Sheets |
|---|---|---|
| 8×10 ft | 288 sq ft | 10 |
| 10×12 ft | 432 sq ft | 15 |
| 12×12 ft | 528 sq ft | 18 |
| 12×15 ft | 612 sq ft | 21 |
| 20×20 ft | 960 sq ft | 33 |