Drywall Calculator — Sheets, Mud & Tape

Start with the walls: add up the perimeter of the room and multiply by the ceiling height. A 12 by 14 foot room has a 52 foot perimeter, and at 8 feet high that is 416 square feet of wall. Then add the ceiling if you are boarding it, which is another 168 square feet in this example, for 584 square feet total. Only subtract openings larger than about 20 square feet — small windows and standard doors are best left in the total, because the offcuts around them rarely get reused.

Choosing sheet length matters more than most people expect. Twelve-foot sheets hung horizontally on an eight-foot wall produce one continuous butt-free seam per wall, which means dramatically less finishing work than eight-foot sheets, which create a butt joint every eight feet. Butt joints are the hardest seams to hide because there is no tapered edge to bury the tape in. If you can get 12 foot sheets into the room, use them.

Budget roughly 0.053 gallons of all-purpose joint compound per square foot of drywall for a standard three-coat finish, which works out to about one 4.5 gallon box per 500 to 600 square feet of board. Paper tape runs about 40 linear feet per 4 × 8 sheet, so a 500 foot roll covers around a dozen sheets. Screws are simpler: 32 per 4 × 8 sheet on 16 inch framing is the standard field-and-edge pattern, and a five pound box holds roughly 500 screws.

Level of finish drives compound usage as much as area does. Level 3 is fine behind heavy texture or tile. Level 4 is the residential standard for flat paint. Level 5 adds a full skim coat over the entire surface and can double your compound order, which is worth doing anywhere raking natural light will cross a large wall or where high-gloss paint is planned.

Material alone is inexpensive: about $16 for a standard 1/2 inch 4 × 8 sheet, $22 for a 4 × 12, and a few dollars more per sheet for moisture-resistant or Type X fire-rated board. Labor is the real cost. Hang and finish work runs $2.00 to $3.50 per square foot of board in most US markets in 2026, which puts a typical 12 by 14 bedroom in the $1,200 to $2,000 range when boarded, taped, sanded and left ready for primer.

The cost variables to watch are ceiling height above nine feet, which triggers scaffolding, curved or vaulted surfaces, and small patch jobs where the setup time dwarfs the material. Many contractors carry a minimum charge of $400 to $600 for small repairs for exactly that reason. This calculator estimates interior finishing quantities only — framing, insulation and electrical rough-in are separate scopes.