How the drywall calculator works
Area = 2 × (length + width) × height + ceiling (length × width)
Sheets = area × (1 + waste) ÷ sheet area, rounded up
Example: a 12 × 12 ft room with 8 ft walls and ceiling
The walls are 384 square feet and the ceiling 144, for 528 in total. With 10% extra that's 580.8 square feet, or 19 sheets of 4 × 8 drywall, about $285 at $15 a sheet. At roughly 32 screws per sheet you'll need about 608 screws.
Frequently asked questions
Should I subtract doors and windows?
Most pros don't for small openings. The offcuts rarely fit elsewhere, so the extra covers waste.
4 × 8 or 4 × 12 sheets?
Longer sheets mean fewer seams to tape, but they're heavy and hard to move through a house alone. 4 × 8 is easiest for DIY.
Last reviewed: 2026-10-31