Drywall Calculator
How many sheets of drywall to buy for one room or a whole house, walls and ceilings, minus doors and windows, plus screws, joint compound and tape.
Wall area = 2 × (length + width) × height; add ceiling (length × width); subtract about 21 sq ft per door and 15 per window; add 10%; divide by 32 for 4 × 8 sheets. A 12 × 12 ft room with 8 ft walls, a ceiling, one door and one window has 492 sq ft and needs 17 sheets of 4 × 8.
Drywall sheets for common rooms (8 ft walls, ceiling, 1 door, 1 window)
| Room | Sq ft of board | 4 × 8 sheets | 4 × 12 sheets |
|---|---|---|---|
| 10 × 10 ft | 384 | 14 | 9 |
| 10 × 12 ft | 436 | 15 | 10 |
| 12 × 12 ft | 492 | 17 | 12 |
| 12 × 14 ft | 548 | 19 | 13 |
| 14 × 16 ft | 668 | 23 | 16 |
| 16 × 20 ft | 860 | 30 | 20 |
Which sheet size?
- 4 × 8: easiest to carry and the only size many trucks and stairs allow.
- 4 × 12: fewer butt joints on long walls and ceilings, so less taping, but two people to hang.
- ½ in for walls, ⅝ in or sag-resistant ½ in for ceilings, moisture-resistant board in bathrooms.
Frequently asked questions
How do I calculate how much drywall I need?
Add up wall areas (perimeter × height) and ceiling areas (length × width), subtract doors (about 21 sq ft each) and windows (about 15 sq ft each), add 10% for waste, and divide by the sheet area: 32 sq ft for 4 × 8, 48 for 4 × 12.
How many sheets of drywall for a 12 × 12 room?
About 17 sheets of 4 × 8 for walls and ceiling with 8 ft walls, one door and one window, or 12 sheets of 4 × 12.
How many drywall screws do I need?
Roughly one screw per square foot of board: about 32 per 4 × 8 sheet with studs 16 in on center. A 1 lb box of 1¼ in screws holds roughly 300.
How much joint compound do I need?
About 0.14 lb of ready-mixed compound per square foot for taping and three coats, so one 4.5 gallon pail (about 62 lb) covers roughly 450 sq ft of board.
How much drywall tape do I need?
About 0.37 ft of tape per square foot of board, roughly 370 ft per 1,000 sq ft. A 250 ft roll covers about 675 sq ft.
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Openings use typical sizes: 3 × 7 ft doors (21 sq ft) and 3 × 5 ft windows (15 sq ft). Screws, compound and tape use common estimating figures (about 1 screw, 0.138 lb of ready-mixed compound and 0.37 ft of tape per sq ft of board). Use thicker or special board where your code requires it (garages, ceilings, fire separations). Prices are placeholders to edit.