How to use this calculator
- Room dimensions. Length, width, and ceiling height — use feet or meters.
- Openings. Subtract doors (~21 ft²) and windows (~15 ft²).
- Sheet size. Default is 4×8 ft. Use 4×12 for fewer seams in long walls.
- Waste. Add 10% for cuts and damaged sheets.
Formula
Sheets = ceil(wall_area / sheet_area × (1 + waste%))
Worked example
A 12 × 14 ft room, 8 ft ceilings, 1 door, 2 windows = 416 ft² of wall. With 10% waste and 4×8 sheets, you need 15 sheets and about 22 gallons of mud.
Tips for accurate results
- Use ½" thick drywall on walls and ⅝" on ceilings (it sags less under its own weight).
- Use moisture-resistant ("green board") in bathrooms; cement board behind tile.
- Plan seams to fall on framing — never have a butt joint between studs.
- Buy 5 lb of screws per 100 ft² of drywall.