Drywall Calculator
Calculate drywall sheets needed for your project including screws, tape, joint compound, and primer. Get material and cost estimates.
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Last updated: January 2026
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Frequently Asked Questions
How do I calculate how much drywall I need?
Measure each wall's length and height, multiply to get square footage, then add all walls together. Subtract window and door openings (standard door = ~20 sq ft, window = ~15 sq ft). Add 10-15% for waste and cuts. Divide by sheet size (4×8 = 32 sq ft, 4×12 = 48 sq ft). Example: Room with 400 sq ft walls, minus 50 sq ft openings = 350 sq ft. With 10% waste = 385 sq ft. Divided by 32 = 12 sheets of 4×8 drywall.
What size drywall sheets should I use?
4×8 foot sheets (32 sq ft) are standard and easier to handle—ideal for DIY and small spaces. 4×12 foot sheets (48 sq ft) reduce seams and are preferred by professionals for walls 9+ feet. Use 4×12 horizontally on tall walls to minimize joints. For ceilings, 4×12 creates fewer seams but requires two people. 1/2-inch thick is standard for walls; 5/8-inch for ceilings or fire-rated applications.
How much waste factor should I add?
Add 10% for simple rectangular rooms with few openings. Add 15% for rooms with many windows, doors, or angles. Add 20% or more for complex layouts, multiple cutouts, or first-time DIYers. Waste comes from: cuts that don't align with sheet sizes, damaged pieces during handling, and mistakes. It's better to have extra than to make another trip to the store mid-project.
What type of drywall do I need for different areas?
Standard (white): Living rooms, bedrooms, hallways—most interior walls. Moisture-resistant (green board): Bathrooms, kitchens, laundry rooms—not for direct water contact. Cement board: Tile backerboard for showers and tub surrounds. Fire-resistant (Type X): Garages, furnace rooms, between units in multi-family—often code-required. Mold-resistant (purple): High-humidity areas, basements. Check local building codes for requirements.
How many screws and how much compound do I need?
Screws: About 28-32 screws per 4×8 sheet (screws every 12 inches on edges, 16 inches in field). Buy 1.25-inch screws for 1/2-inch drywall, 1.5-inch for 5/8-inch. Joint compound: About 1 gallon per 100 sq ft of drywall for taping and three finishing coats. Tape: About 375 feet per 1,000 sq ft (tape all seams plus corners). A typical 12×12 room uses about 12 sheets, 400 screws, 1.5 gallons compound, and 50 feet of tape.