Drywall Sheet Calculator
Estimate how many drywall sheets you need for a room, plus joint compound (mud), tape and screws. Enter the room dimensions in feet; the calculator subtracts standard door and window openings, optionally includes the ceiling, and adds a waste factor — 10% for straight walls, 15% for cut-heavy layouts.
How the estimate works
Wall area = 2 × (length + width) × height. Each door subtracts 21 sq ft and each window 15 sq ft. The ceiling adds length × width. Sheets = area × (1 + waste%) ÷ sheet size, rounded up. Materials follow standard coverage: one 4.5-gal bucket of compound per ~350 sq ft, one 500-ft tape roll per ~1,000 sq ft of board, and about 1 lb of screws per 50 sq ft.
Sheet sizes
| Sheet | Coverage | Typical use |
|---|---|---|
| 4 × 8 ft | 32 sq ft | Standard walls, easiest to handle |
| 4 × 12 ft | 48 sq ft | Fewer seams on long walls and ceilings |
Frequently asked questions
How many drywall sheets do I need for a 12×12 room?
A 12×12 ft room with 8 ft walls has 384 sq ft of wall; subtract one door and one window (36 sq ft) for 348 sq ft, plus a 144 sq ft ceiling = 492 sq ft. With 10% waste and 4×8 sheets that is 17 sheets.
What waste factor should I use for drywall?
Use 10% for simple rectangular rooms with straight walls, and 15% for rooms with many corners, angles, or cut-heavy layouts like stairwells and closets.
How much joint compound per sheet of drywall?
Plan on one 4.5-gallon bucket of all-purpose compound per ~350 sq ft of board — roughly one bucket per 11 sheets of 4×8 drywall for a standard 3-coat finish.
Should I use 4×8 or 4×12 sheets?
4×12 sheets mean fewer joints to tape and finish, giving flatter walls — but they are heavy and awkward in small rooms. Use 4×12 on long uninterrupted walls and ceilings if you can transport them; otherwise 4×8 is the practical default.