How to calculate drywall
Sheets = (walls + ceiling − openings) × 1.1 ÷ sheet area
Worked example. Sheets needed: 21 4×8 sheets.
Example inputs — Room length (ft): 16; Room width (ft): 12; Wall height (ft): 8; Include ceiling?: Yes; Doors & windows (sq ft): 40; Sheet size: 4 × 8 ft. Starting values are illustrative.
Includes 10% extra for cuts and mistakes
From George Guju, founder of Calculyn · Educational calculator guidance, not professional advice.
How it works
Add up wall and ceiling area, subtract doors and windows, then divide by the sheet size and add 10% for waste.
Assumptions & limitations
- Standard waste factor of 10%; complex rooms with many corners may need more.
Formula and assumptions reviewed October 2026 by the Calculyn team. How we build our calculators
Frequently asked questions
4×8 or 4×12 sheets?
4×12 sheets mean fewer seams on long walls but are heavier and harder to handle.