Drywall Calculator
Calculate sheets, tape, and joint compound for a room takeoff — with door and window deductions and waste factor built in.
21 sqft deducted each
15 sqft deducted each
10% standard; 15% for complex rooms
Sheets Needed
17 sheets
4x8 · 480 net sqft · ~$238 materials
| Wall Area | 396 sqft |
| Door Deduction (1) | −21 sqft |
| Window Deduction (1) | −15 sqft |
| Ceiling Area | 120 sqft |
| Net Area | 480 sqft |
| Sheets (10% waste) | 17 sheets |
| Drywall Tape | ~595 linear ft |
| Joint Compound | ~26 lbs |
| Est. Material Cost | ~$238 |
Wall area = perimeter × height. Subtract 21 sqft per door and 15 sqft per window. Add ceiling if selected. Sheets = net area ÷ sheet size, rounded up, with waste factor applied. Joint compound at 0.053 lbs/sqft for all three coats. Material cost estimate uses average retail pricing and will vary by region and supplier.
Frequently Asked Questions
How many sheets of drywall do I need for a 12×10 room?
For a 12×10 room with 9-ft ceilings, one door, and one window: walls = 2 × (12+10) × 9 = 396 sqft. Minus 1 door (21 sqft) and 1 window (15 sqft) = 360 sqft of walls. Ceiling = 120 sqft. Total = 480 sqft ÷ 32 sqft per sheet × 1.10 waste = 17 sheets of 4×8 drywall.
What size drywall sheets should I buy?
4×8 sheets are standard for most residential work and easiest to handle solo. 4×12 reduces the number of seams and butt joints, which speeds hanging and taping on long walls — preferred by production framers. 4×10 is a middle option for 9–10 ft ceilings to reduce horizontal seams.
How much joint compound do I need?
Plan on about 0.05 lbs of compound per square foot of drywall for all three coats (tape coat, second coat, finish coat). A typical 5-gallon bucket of all-purpose compound weighs about 60 lbs and covers roughly 1,200 sqft. Don't forget corner bead, which adds compound usage.
Should I include waste in my drywall order?
Yes — always add waste. Use 10% minimum for standard rectangular rooms. Add 15% for rooms with many angles, arched doorways, vaulted ceilings, or cathedral walls. Drywall cuts often leave off-cuts too small to reuse, and returning partial sheets is usually not practical.