Drywall Sheet Count and Waste Calculator
Calculate the number of drywall sheets required for walls and ceilings, accounting for doors, windows, and waste.
Formulas Used
Gross Wall Area = 2 × (Length + Width) × Ceiling Height
Opening Deductions = (Number of Doors × 17.78 ft²) + (Number of Windows × 12 ft²)
Net Wall Area = Gross Wall Area − Opening Deductions
Ceiling Area = Length × Width (if ceiling is included)
Total Net Area = Net Wall Area + Ceiling Area
Sheet Area = Sheet Width × Sheet Length
Sheets (no waste) = ⌈ Total Net Area ÷ Sheet Area ⌉
Sheets Needed = ⌈ (Total Net Area ÷ Sheet Area) × (1 + Waste% ÷ 100) ⌉
Assumptions & References
- Standard door opening assumed to be 32 in × 80 in (≈ 17.78 ft²) per IRC Section R311.
- A 10% waste factor is typical for rectangular rooms; increase to 15–20% for rooms with many angles, arches, or complex cuts (NAHB Remodeling Cost Guide).