Drywall Calculator

Find out how many sheets of drywall you need for a room. Enter the room size and wall height, the number of doors and windows, and the sheet size, and add the ceiling if you're covering it too.

Drywall sheets

Area to cover: 317 sq ft
Screws (approx.): 317

Results are estimates for information only and do not constitute financial, medical, or legal advice.

How it works

The calculator adds up the area of the four walls, subtracts the doors and windows, adds the ceiling if you check it, and adds the extra you choose for waste. Then it divides by the area of one sheet and rounds up.

The formulas

Walls = 2 × (length + width) × height − openings

Sheets = area × (1 + waste) ÷ sheet area, rounded up

Worked example

A 12 × 10 ft room with 8 ft walls, one door, and one window, using 4 × 8 sheets and 10% extra.

Walls: 2 × (12 + 10) × 8 = 352 sq ft, minus 20 for the door and 15 for the window = 317 sq ft.
With 10% extra: 348.7 sq ft.
Sheets: 348.7 ÷ 32 = 10.9, so 11 sheets.

Frequently asked questions

Which drywall sheet size should I use?

4 × 8 ft sheets are the easiest to carry and fit most 8-foot walls standing up. Longer 4 × 10 and 4 × 12 sheets mean fewer seams to tape on long walls and ceilings, but they are heavier and harder to handle alone.

Should I subtract doors and windows?

The calculator subtracts a standard area for each (20 sq ft per door and 15 sq ft per window). Many pros don't subtract small windows at all, because the cutouts are usually waste anyway. The extra percentage covers that.

How much joint compound and tape will I need?

A common rule of thumb is about 1 gallon of premixed joint compound and around 40 feet of tape for every 100 square feet of drywall, but it depends on how many seams and corners you have.