Drywall Calculator
Enter your room's dimensions and this calculator figures the wall area (plus the ceiling if you want it), subtracts door and window openings, adds waste, and converts it to a sheet count.
This assumes a simple rectangular room. For multiple rooms, hallways or rooms with alcoves, calculate each space separately and add the sheet counts. Many hangers don't subtract small windows at all — the cutout scrap often isn't reusable.
How this is calculated
Wall area = 2 × (length + width) × height. Ceiling area = length × width, if included.
Sheets = (wall area + ceiling area − openings) × (1 + waste ÷ 100) ÷ sheet area, rounded up. A 4×8 sheet is 32 sq ft; a 4×12 sheet is 48 sq ft.
Common questions
Which sheet size should I use?
4×8 sheets are the easiest to handle and fit most cars and stairwells. Longer sheets (4×10, 4×12) mean fewer joints to tape but are heavy and awkward — common on pro jobs with ceilings over 8 feet or long walls.
Should I really subtract windows and doors?
Subtract large openings like garage doors and sliders. For normal doors and windows, many people don't subtract anything and treat that area as their waste cushion instead. Either approach works if you're consistent.
How much waste is normal?
Around 10% for straightforward rooms. Rooms with angles, soffits or many openings generate more offcuts.
Does this include joint compound, tape or screws?
No — it counts sheets only. Supplier guides on mud and screw quantities per square foot vary by product, so check the packaging for those.