About this calculator
This drywall calculator totals the wall (and optionally ceiling) area of a rectangular room and converts it into full sheets of drywall, with an allowance for waste. It also estimates the finishing materials: screws, ready-mixed joint compound and paper tape, using the coverage rates gypsum manufacturers publish for a standard Level 4 finish.
How to use it
- Enter the room’s length, width and wall height.
- Choose whether to include the ceiling.
- Pick a sheet size. Longer sheets mean fewer seams to tape but are heavier to handle.
- Keep 10% extra. Pros usually don’t subtract doors and windows — cut-outs rarely produce usable pieces.
The formula
Area = 2 × (length + width) × height [+ length × width for the ceiling]
Sheets = area × (1 + extra%) ÷ sheet area, rounded up
Screws ≈ 1 per sq ft · Compound ≈ 1 gal per 100 sq ft · Tape ≈ 370 ft per 1,000 sq ft
The finishing figures come from USG’s estimating guidance for a three-coat (Level 4) finish. Heavier textures or a Level 5 skim coat use considerably more compound.
Worked example
These are the calculator’s starting values and the results they produce:
| Room length | 14 ft |
|---|---|
| Room width | 12 ft |
| Wall height | 8 ft |
| Include the ceiling? | Yes |
| Sheet size | 4 × 8 ft (32 sq ft) |
| Extra for waste | 10 % |
Tips before you buy
- Hang ceilings first, then walls, with wall sheets tight up against the ceiling.
- On walls, run sheets horizontally — it usually means fewer and easier-to-finish seams.
- Use ⅝ in fire-rated (Type X) board where code requires it, such as garage walls shared with the house.
- Use moisture-resistant board or cement board in bathrooms and behind tile.
Frequently asked questions
How many sheets of drywall do I need for a 12×12 room?
A 12 × 12 room with 8 ft walls has 384 sq ft of wall and 144 sq ft of ceiling — 528 sq ft in total. With 10% extra that is 19 sheets of 4 × 8 drywall, or 13 sheets of 4 × 12.
How many screws per sheet of drywall?
About 28–32 screws per 4 × 8 sheet on walls with studs 16 in on center, and a few more on ceilings, where screws are spaced closer. Budget roughly one screw per square foot.
How much joint compound do I need?
About 1 gallon of ready-mixed compound per 100 sq ft of drywall for a standard three-coat finish — so a typical 4.5-gallon box finishes about 450 sq ft.