Drywall Calculator
How many sheets of drywall do I need? Sheets, mud, tape and screws for any room.
How to calculate drywall sheets
- Find the area to cover. Walls: room perimeter × wall height. Add the ceiling (length × width) if you are boarding it too.
- Subtract openings. Standard doors (~21 sq ft) and windows (~15 sq ft) come off the total.
- Add waste. 10% covers cuts and breakage in a simple room; angled walls and soffits push it to 15%.
- Divide by sheet area. A 4×8 sheet covers 32 sq ft, 4×10 covers 40, 4×12 covers 48. Round up.
Formula: sheets = ⌈(area − openings) × (1 + waste%) ÷ sheet area⌉
What about mud, tape and screws?
Finishing materials scale with the drywall area, and the trade rules of thumb are consistent:
- Joint compound: one 4.5-gal (61 lb) ready-mix bucket per ~450 sq ft (~42 m²) for a three-coat finish.
- Screws: ~1 per sq ft — about 32 per 4×8 sheet at 16 in stud spacing.
- Tape: ~370 ft per 1,000 sq ft of board — one 250 ft roll handles a typical room.
Choosing a sheet size
4×8 ft is the DIY default: manageable weight and fits in most vehicles and stairwells. 4×12 ft reduces the number of joints you must tape and finish — the slowest part of the job — but sheets are heavy and need two people. Use 4×10 or 4×12 horizontally on long walls to eliminate vertical seams where possible.
Frequently asked questions
What size drywall sheet should I use?
4×8 ft is standard for DIY — light enough to handle alone. 4×12 means fewer joints to finish but needs two people. Metric markets commonly use 1.2 × 2.4 m sheets.
How much joint compound do I need?
Roughly one 4.5-gallon bucket per 400–500 sq ft of drywall for a standard three-coat finish. Texture and skim coats use significantly more.
How many screws per sheet?
About 32 per 4×8 sheet with studs at 16 in on center — roughly one per square foot. Ceilings often require closer spacing.
Should I subtract doors and windows?
Subtract standard ones and let the waste factor absorb the cutting loss around them. Subtract very large openings (garage doors, window walls) at their real size.