Drywall Calculator
Enter your total wall area or room dimensions to find out how many sheets of drywall to buy, plus joint compound and tape.
1. Wall area
Wall area: 384 sq ft
2. Openings to subtract
21 sq ft each
15 sq ft each
3. Sheet size, waste & price
Your Drywall Estimate
12
sheets
4
joint compound (gal)
4
tape rolls (75 ft)
Calculation breakdown
Gross wall area: 384 sq ft
Openings: −51 sq ft
Net area: 333 sq ft
With 12% waste: 373 sq ft
Sheets: 373 ÷ 32 sq ft/sheet = 12 sheets
Joint compound and tape estimates cover 3 coats. Actual usage varies with experience level and application method.
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How to measure for drywall
- 1. Measure all walls: For each wall, measure length × height. Add them all together for total wall area.
- 2. Add the ceiling: If drywalling the ceiling too, add length × width of the room to your wall area.
- 3. Count openings: Subtract standard doors (21 sq ft) and windows (15 sq ft). Don't over-deduct — you'll use the cutoffs for other spots.
- 4. Sheet size tip: 4×12 sheets mean fewer seams and a smoother finish, but are heavier and harder to maneuver alone.
Frequently Asked Questions
How many sheets of drywall do I need for a 12×12 room?
A 12×12 ft room with 8 ft ceilings needs about 17 sheets of 4×8 drywall (walls + ceiling). This includes 12% waste for cutouts. Joint compound: ~2 gallons. Tape: ~6 rolls.
What thickness drywall should I use?
1/2 inch for most interior walls and ceilings. 5/8 inch (Type X) for garage walls, fire-rated assemblies, and between garage and living space. Use moisture-resistant 1/2 inch in bathrooms.
How much joint compound do I need?
Plan for about 1 gallon of pre-mixed joint compound per 100 sq ft of drywall for a 3-coat tape-and-finish job. A 4.5 gallon bucket covers approximately 450 sq ft.
How do I calculate drywall for a room?
Wall area = Perimeter × Wall height. Ceiling area = Length × Width. Add both, subtract door (21 sq ft each) and window (15 sq ft each) areas, then add 12% waste. Divide by sheet size.
Sheets = ceil(net area × 1.12 ÷ sheet sq ft). Joint compound: 1 gal/100 sq ft (3 coats, USG avg). See our methodology page.