Drywall Calculator
Calculate drywall sheets, joint compound, and tape needed for any room.
Enter room dimensions, doors, and windows for an accurate estimate.
How to Estimate Drywall
Drywall (also called sheetrock or plasterboard) is installed on walls and ceilings in large sheets, then taped, mudded, and sanded to a smooth finish. Accurate estimation prevents costly over-purchasing while ensuring you have enough material to complete the project without visible color or texture differences.
Calculating Wall and Ceiling Area
Total wall area = perimeter of the room × ceiling height. Ceiling area = length × width. From this total, subtract the area of doors (typically 21 square feet each for a standard 3×7 ft door) and windows (varies, but a typical window is 8–15 square feet). Drywall is sold in sheets, most commonly 4×8 feet (32 square feet each), though 4×10 and 4×12 are available for high ceilings. Divide net area by sheet area, then add 10–15% for waste from cuts around outlets, corners, and openings.
Joint Compound (Mud)
Joint compound is used to cover the paper tape over seams, fill screw dimples, and apply finish coats. A standard drywall installation requires three coats of compound: tape coat, fill coat, and finish coat. A 4.5-gallon bucket of premixed joint compound (approximately 50 lbs) covers roughly 100 square feet of finished drywall with all three coats. For repairs and small projects, a 1-gallon bucket (approximately 12 lbs) is more economical.
Tape
Paper drywall tape is placed over all seams before the first coat of compound. One roll of paper tape (500 feet) covers approximately 500 linear feet of seams. In a typical room, each sheet creates roughly 4–8 feet of seam (shared with adjacent sheets), so tape usage is roughly proportional to the number of sheets.
Screws
Drywall screws are installed every 12 inches on studs for walls and every 8 inches for ceilings. A 5-lb box of 1-5/8 inch coarse-thread drywall screws covers approximately 500–600 square feet of drywall.
Safety
Wear a dust mask when cutting drywall — the gypsum dust is fine and irritating. Cut with a utility knife by scoring and snapping rather than sawing to minimize dust. Always dispose of drywall offcuts according to local regulations; gypsum should not go to landfill in many jurisdictions.