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How the Drywall Calculator works
This calculator answers how many sheets of drywall you need for a room's walls, with or without the ceiling, and gives rough amounts of screws, joint compound and paper tape to finish it.
Wall area = 2 × (length + width) × wall height, minus doors and windows; add length × width if the ceiling is included. Multiply by 1 + waste (10% by default), divide by the sheet area (4×8 = 32 sq ft, 4×10 = 40, 4×12 = 48) and round up. Finishing amounts follow USG rules of thumb per 1,000 sq ft of board: about 1,000 screws on framing 16" on center, 10 gal of ready-mixed all-purpose compound and 370 ft of paper tape.
Example: a 12' × 10' room with 8' walls, one 3' × 6' 8" door and two 3' × 4' windows. Walls: 2 × (12 + 10) × 8 = 352 sq ft, minus 20 + 24 = 44 sq ft of openings = 308 sq ft. Ceiling: 12 × 10 = 120 sq ft, for 428 sq ft in all. With 10% waste that is 470.8 sq ft ÷ 32 = 14.7, so 15 sheets of 4×8 (or 470.8 ÷ 48 = 9.8, so 10 sheets of 4×12). Finishing: about 428 screws, 4.3 gal of compound (one 4.5 gal pail) and 158 ft of tape (one 500 ft roll).
The count is by area, so it does not lay out each sheet. Longer sheets leave fewer butt joints to tape, and walls taller than 8' need an extra strip or larger sheets. If you would rather not count on the cutouts from windows, enter 0 windows for a safer number. Screws drop to about 850 per 1,000 sq ft on framing 24" on center.
Frequently asked questions
How many sheets of drywall do I need for a 12x12 room?
With 8' walls and nothing subtracted for doors or windows, the walls are 2 × (12 + 12) × 8 = 384 sq ft and the ceiling 144 sq ft, 528 sq ft in all. Add 10% (580.8 sq ft) and divide by 32: 18.15, so 19 sheets of 4×8. The walls alone take 14 sheets (422.4 ÷ 32 = 13.2).
How many square feet is a sheet of drywall?
A 4×8 sheet is 32 sq ft, a 4×10 is 40 sq ft and a 4×12 is 48 sq ft. Divide your total area (plus waste) by that number and round up to get the sheet count.
How many screws do I need per sheet of drywall?
USG's rule of thumb is about 1,000 screws per 1,000 sq ft of board on framing 16" on center, about one per square foot or roughly 32 per 4×8 sheet. On framing 24" on center it is closer to 850 per 1,000 sq ft. Follow the fastener spacing for your board and assembly.
How much joint compound and tape do I need?
Plan on about 10 gallons of ready-mixed all-purpose compound and 370 ft of paper tape per 1,000 sq ft of board (USG). A 428 sq ft room needs about 4.3 gallons, one 4.5 gal pail, and 158 ft of tape, one 500 ft roll. A higher level of finish or a skim coat uses more.