How to calculate drywall
Drywall is estimated by area. Add up the surface you are covering and divide by the size of one sheet:
Sheets = total area × (1 + waste %) ÷ sheet coverage
Wall area is the room perimeter times the wall height: 2 × (length + width) × height. Tick "Include the ceiling" to add the floor-sized area overhead. Most DIYers don't subtract small openings — that buffer covers waste.
Drywall sheet sizes
| Sheet size | Coverage | Best for |
|---|---|---|
| 4 × 8 ft | 32 sq ft | Easiest to handle; most rooms |
| 4 × 10 ft | 40 sq ft | Taller walls, fewer seams |
| 4 × 12 ft | 48 sq ft | Large walls and ceilings |
Don't forget the finishing materials
- Screws: about one per square foot (≈32 per 4×8 sheet) at 16-inch framing spacing.
- Joint compound & tape: needed for every seam and screw head — check the bucket for coverage.
- Corner bead: measure each outside corner separately.