How Much Do I Need?

Drywall Calculator

How many sheets of drywall do I need?

Enter the size of the room and the sheet size you plan to hang. The calculator works out the wall area, takes off doors and windows, adds the ceiling if you want it, and rounds up to whole sheets.

Units
Room size
Doors and windows
Sheets

Common sizes: 4 × 8, 4 × 10 and 4 × 12 ft, or 1.2 × 2.4 m.

For cuts around openings and damaged corners. 10–15% is common.

Cost (optional)

Add the price to see an estimated total.

Results update as you type.

Your estimate

Drywall to buy

16 sheets

4 ft × 8 ft sheets for 437 ft², including 10% waste.

Estimated amount to buy

Sheets (4 ft × 8 ft)
16
Drywall screws (rule of thumb)
512

Calculated quantity (no waste)

Walls after openings
317 ft²
Ceiling
120 ft²
Area to cover
437 ft²
Sheets
13.66
How this was calculated
  1. Wall area = 2 × (12 ft + 10 ft) × 8 ft = 352 ft²
  2. Doors and windows = 1 × 20 ft² + 1 × 15 ft² = 35 ft²
  3. Ceiling = 12 ft × 10 ft = 120 ft²
  4. Area to cover = 352 ft² − 35 ft² + 120 ft² = 437 ft²
  5. Sheets = 437 ft² ÷ 32 ft² per sheet = 13.66
  6. With 10% waste = 13.66 × 1.1 = 15.03, rounded up to 16
  7. Screws ≈ 16 sheets × 32 ft² × 1 per ft² = 512
  • Joint tape and compound are extra. Ceilings often use thicker or sag-resistant board; check local codes for fire-rated board in garages.

How the drywall calculation works

  1. Wall area = 2 × (length + width) × wall height.
  2. Subtract doors and windows (count × area of each).
  3. Add the ceiling (length × width) if you're boarding it.
  4. Sheets = area ÷ area of one sheet, then the waste allowance, rounded up.
  5. Screws are estimated with a common rule of thumb of about one screw per square foot of board (about 32 for a 4 × 8 sheet). Your fixing pattern and local code decide the real number.

Choosing sheet sizes

Longer sheets (10 or 12 ft) mean fewer joints to tape and a flatter finish, but they are heavier and harder to carry through a house. Hanging sheets horizontally on walls is common because it reduces joint length. The area-based count here doesn't depend on orientation, but very tall or narrow walls can create more offcuts, so raise the waste allowance for rooms with lots of corners.

Rounding rules

  • Sheets are rounded up to whole sheets after the waste allowance.
  • Screws are a rounded-up estimate.