How this drywall calculator works
The calculator divides your total wall and ceiling area by the area of one sheet, adds a waste allowance for cuts and breakage, and estimates the finishing materials from proven rules of thumb: about one screw per square foot (11 per m²), 0.053 lb of ready-mix joint compound per square foot (0.26 kg/m²), and 0.37 feet of tape per square foot of board.
Choosing sheet size
Standard sheets are 4 feet (1.2 m) wide and 8, 10 or 12 feet long (2.4/3/3.6 m). Longer sheets mean fewer joints to tape and a flatter wall, but they're heavy and awkward through doorways and stairwells. Use ½ inch (12.5 mm) board for walls, ⅝ inch (15 mm) fire-rated where code requires it, and moisture-resistant (green) board in bathrooms and laundry rooms.
Measuring the area
For walls, multiply the perimeter of the room by the ceiling height; for ceilings, length times width. Don't subtract standard doors and windows — the offcuts around openings are rarely reusable, which is exactly what the waste allowance is for. Only deduct very large openings like garage doors or full window walls.
Finishing materials in practice
Compound consumption spans three coats: tape coat, fill coat and skim coat. Buy ready-mix in buckets for convenience or setting-type powder for the first coat's strength. Paper tape is stronger for flat joints and corners; mesh tape is easier for small patches but wants setting compound. One roll of tape is typically 250 ft (75 m).