Drywall Calculator
Estimate drywall area, sheets needed, waste allowance, and approximate material cost for wall and ceiling projects.
Enter your room measurements, drywall sheet size, and local price to create a project estimate.
🌎 Region
Choose the country for currency labels. Switching regions does not convert USD and CAD or update local prices.
📐 Room Size
Enter the room footprint and wall height for the drywall estimate.
🧱 Drywall Area
Include the ceiling if you also plan to install drywall above the room.
🚪 Doors and Windows
Planning areas of 21 sq ft per door and 12 sq ft per window are deducted from the estimate. Actual openings vary.
💵 Sheet and Pricing
Enter drywall sheet size, waste allowance, and material price per sheet.
Enter project details
Add the room dimensions and drywall sheet size to see the estimated area, sheet count, and material cost.
Estimate disclaimer: This estimate is for planning purposes only. Actual costs may vary based on location, material prices, labor rates, taxes, fees, exchange rates, and project conditions.
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📘 How It Works
This drywall calculator estimates wall area, optional ceiling area, door and window deductions, waste allowance, sheet count, and approximate material cost based on your room dimensions and drywall sheet size.
Wall Area: 2 × (Length + Width) × Wall Height
Ceiling Area: Length × Width, if ceiling is included
Net Drywall Area: Wall Area + Ceiling Area − Door and Window Deduction
Applied Opening Deduction: The smaller of the planning opening deduction and the total wall-plus-ceiling area
Area With Waste: Net Drywall Area × (1 + Waste Percentage ÷ 100)
Sheets Needed: Area With Waste ÷ Sheet Area, rounded up
🎯 When to Use
- 🏠 Estimating drywall for bedrooms, offices, basements, and renovation projects
- 📐 Calculating wall area and optional ceiling area from room dimensions
- 🚪 Applying disclosed planning deductions for doors and windows
- ✂️ Adding waste allowance for cuts, seams, corners, and layout adjustments
- 💵 Estimating approximate drywall sheet cost in US or Canada mode
🧮 Worked drywall calculation example
Example: a 12 × 15 ft rectangular room with 8 ft walls, the ceiling included, one 21 sq ft door deduction, two 12 sq ft window deductions, 10% waste, 4 × 8 ft sheets, and $15 per sheet.
Wall area = 2 × (12 + 15) × 8 = 432 sq ft
Ceiling area = 12 × 15 = 180 sq ft
Opening deduction = 21 + (2 × 12) = 45 sq ft
Net area = 432 + 180 − 45 = 567 sq ft
Area with waste = 567 × 1.10 = 623.7 sq ft
Sheet area = 4 × 8 = 32 sq ft
Sheets needed = ceil(623.7 ÷ 32) = 20
Estimated total sheet cost = 20 × $15 = $300.00
📋 Assumptions and limitations
- The room is treated as a simple rectangle.
- Interior partitions, closet interiors, sloped walls, vaulted ceilings, and multiple board layers are excluded.
- The model uses optional planning deductions of 21 sq ft per door and 12 sq ft per window. Actual openings vary, and some methods do not subtract openings because offcuts and layout waste may offset them.
- The applied opening deduction is capped at the total wall and included-ceiling area, so net drywall area cannot become negative.
- Whole-sheet count is based on total area and cannot guarantee a practical board layout for every surface.
- Joint compound, tape, screws, corner bead, tax, delivery, and labor are excluded.
- US and Canada modes change currency labels only; they do not convert prices or change the formula.
- Select board thickness, type, and installation methods appropriate for the project and applicable building requirements.
📚 Sources and methodology
The area method and opening-deduction limitations were reviewed against manufacturer estimating and installation guidance.
- USG Sheetrock Wallboard Estimator
- USG Sheetrock Gypsum Panels Installation Guide
- CertainTeed Drywall Calculator
Calculation version: Drywall Calculator V2
Last reviewed: August 15, 2026
Maintained by: FigureNorth Editorial Team
Method: Rectangular-room surface-area estimate
Review status: Formula and educational content reviewed
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❓ FAQ
How many drywall sheets do I need?
The estimate depends on rectangular-room dimensions, ceiling inclusion, optional opening deductions, waste allowance, and sheet size. The final area is divided by sheet area and rounded up to a whole sheet.
Should I subtract doors and windows?
This calculator optionally uses planning deductions of 21 square feet per door and 12 square feet per window. Actual openings vary, and some estimating methods do not subtract openings because layout waste and offcuts may offset them.
What waste percentage should I use?
The calculator defaults to 10% as an editable planning allowance, not a universal requirement. Simple layouts may need less, while closets, corners, angled surfaces, patchwork, damage, and complicated board layouts may need more. Use a value appropriate for the project and supplier guidance.
Does this include labor or finishing materials?
No. It estimates drywall sheets and sheet cost only. Joint compound, tape, screws, corner bead, taxes, delivery, and labor are excluded.
What changes between United States and Canada mode?
The region control changes USD and CAD labels only. It does not convert currencies, update local prices, or change the area formula.