Drywall Calculator

How the drywall estimate works

Drywall is sold in sheets, so the job is mostly an area problem. The wall area is the room perimeter multiplied by the wall height: 2 × (length + width) × height. The ceiling area is length × width. Subtract the area of doors and windows from the walls, add a waste allowance for cuts and mistakes, and divide by the area of one sheet. Always round up, because you cannot buy part of a sheet. A 12 × 10 ft room with 8 ft walls and 40 sq ft of openings needs 312 sq ft of wall covering.

Larger sheets such as 4×12 ft mean fewer seams and less taping, but they are heavy and awkward to carry. Hanging sheets horizontally across studs on tall walls is a common way to reduce vertical joints.

Compound, tape and screws

Besides sheets, you need finishing materials. The calculator estimates joint compound at about 0.053 gallons per square foot, paper or mesh tape at roughly 0.37 feet per square foot, and about 1.3 screws per square foot, which corresponds to fasteners every 12 inches along the studs. Buy a little extra of each, since compound is also used for corners and fixing mistakes.

Tips for ordering

Measure each room separately if the shape is irregular, and add the results together. Use a higher waste percentage when you have many windows, angled walls or a diagonal layout. Check whether your local code requires 5/8 inch fire-rated board on garage ceilings or shared walls, because it changes the cost but not the quantity. Remember that thicker boards weigh more, so plan to have help lifting ceiling sheets. All the math runs in your browser and nothing you enter is uploaded.

Example: for the 12 × 10 ft room above with a 10 percent waste allowance, the walls need about 343 sq ft of board, which is 11 sheets of 4×8 ft drywall. Choosing 4×12 ft sheets would reduce this to 8 sheets and remove several seams.