Drywall Calculator
Enter the room size and choose a sheet size to see how many drywall sheets to buy, with screws, joint tape and joint compound for finishing.
Enter the room length, width and wall height.
On this page
How to use the drywall calculator
- Measure the room at floor level and the wall height. For several rooms, run the calculator once per room.
- Decide about openings. Pros usually don't subtract doors and windows — the offcuts rarely fit elsewhere, so the "missing" area becomes your waste allowance. Subtract only big openings such as a garage door or a wide archway.
- Choose the sheet size. Longer sheets mean fewer joints to tape but are heavier and harder to carry through a house.
How to calculate drywall
Worked example: a 12 × 12 ft room with 8 ft walls, walls and ceiling
- Walls: 2 × 24 × 8 = 384 sq ft; ceiling: 144 sq ft; total 528 sq ft
- With 10% extra: 580.8 sq ft ÷ 32 = 18.2 → 19 sheets of 4 × 8
- Screws: about 600; joint tape: about 200 ft
Sheets per room
| Room (8 ft walls) | Walls only (4×8 sheets) | Walls + ceiling (4×8 sheets) |
|---|---|---|
| 10 × 10 ft | 11 | 15 |
| 12 × 12 ft | 14 | 19 |
| 12 × 16 ft | 16 | 22 |
| 15 × 20 ft | 20 | 30 |
Including 10% extra, no openings subtracted.
Choosing sheets and thickness
- ½ in is the standard for interior walls; lightweight ½ in panels are easier to handle.
- ⅝ in Type X is fire-rated and is often required on garage walls and ceilings shared with living space — check your local code.
- Moisture-resistant panels suit bathrooms and laundry rooms, but use cement board or a waterproof membrane behind tile in showers.
- Ceilings: use panels rated for ceilings (often ½ in sag-resistant) and closer screw spacing.
Finishing materials
USG estimates roughly 370 feet of joint tape per 1,000 square feet of board. Joint compound use varies with the product and the level of finish; as a guide, USG notes that about two 4.5-gallon pails of its UltraLightweight ready-mixed compound finish 1,000 square feet. Buy a little more than you think — running out between coats is frustrating — and check the coverage on the product you choose.
Frequently asked questions
How many sheets of drywall for a 12 × 12 room?
With 8 ft walls: 14 sheets of 4 × 8 for the walls alone, or 19 including the ceiling, with 10% extra.
How many screws per sheet of drywall?
About 32 for a 4 × 8 sheet on walls with studs 16 inches apart; ceilings need closer spacing and more screws.
Should I use 4×8 or 4×12 sheets?
4×12 sheets cover a typical wall with fewer butt joints, which saves taping time. 4×8 sheets are easier to carry and handle alone.
Sources
- USG — estimating figures for joint tape and ready-mixed joint compound.