How to calculate how much drywall you need
Drywall is sold by the sheet, so the job is to find your total wall area and divide by how much one sheet covers. The main choice is sheet size — 4x8 sheets are easier to handle alone, while 4x12 sheets mean fewer seams to tape.
wall area = 2 × (length + width) × height
sheets = round up((wall area × 1.10) ÷ sheet size)
Worked example
A 12 ft × 10 ft room with 8 ft walls has 2 × (12 + 10) × 8 = 352 sq ft of wall. Add 10% waste for cuts and you need to cover about 387 sq ft. At 32 sq ft per 4x8 sheet, that's 12.1 sheets — and since you can't buy part of a sheet, you round up to 13.
How many screws and how much mud per sheet?
Beyond the sheets themselves, three supplies scale with your drywall total:
| Supply | Rule of thumb | Notes |
|---|
| Drywall screws | ~32 screws per sheet | 1.25" for a single layer |
| Joint compound | 1 gal per ~100 sq ft | Buckets are usually 4.5 gal |
| Joint tape | 1 roll (250 ft) per ~500 sq ft | Paper tape is standard |
Frequently asked questions
How many sheets of drywall do I need for a 12x10 room?
A 12 by 10 room with 8-foot walls needs 13 sheets of standard 4x8 drywall once you include a 10% waste allowance for cuts and round up to whole sheets.
Is 4x8 or 4x12 drywall better?
4x8 sheets are lighter and easier for one person to hang. 4x12 sheets cover more per sheet and create fewer seams to tape, but are heavier and usually need two people.
How much drywall mud do I need?
Plan on roughly one gallon of joint compound per 100 square feet of drywall for a standard three-coat finish, though texture and finish level can change this.
What size screws for drywall?
1.25-inch drywall screws are standard for a single layer of 1/2-inch drywall over wood studs. Use 1.625-inch screws over metal studs or for thicker board.