Drywall Calculator

Drywall (also called plasterboard or gypsum board) covers the walls and ceilings of a room to create a smooth, paintable surface — and buying the right amount means knowing exactly how many sheets your project needs. Enter your room length, room width, and ceiling height, then add the number of doors and windows with their sizes so openings are deducted from the total. Select your drywall sheet size and waste factor to get the number of sheets needed, along with total wall area, area after openings, and area per sheet.

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Results

Drywall Sheets Needed

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Total Wall Area

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Area After Openings

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Area per Sheet

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Frequently Asked Questions

How do I measure my room for drywall?

Measure the length and width of the room, then multiply by ceiling height to get wall area. Measure each wall separately for irregular rooms and add them together.

Should I subtract door and window areas?

Yes, subtract door and window openings from your total wall area to get a more accurate estimate. Standard doors are about 21 sq ft and typical windows are 9-12 sq ft.

What size drywall sheets should I use?

4'×8' sheets are most common and easiest to handle. 4'×10' or 4'×12' sheets can reduce seams but are heavier and harder to install, especially for DIYers.

How much extra drywall should I buy?

Add 5-10% extra for professional installations, or 10-15% for DIY projects to account for cuts, mistakes, and future repairs. Complex layouts may need more waste allowance.

Do I need different drywall for different rooms?

Standard 1/2" drywall works for most rooms. Use moisture-resistant drywall in bathrooms and basements, and 5/8" drywall for fire-rated walls or better soundproofing.

How many screws do I need per drywall sheet?

Plan for about 28-32 screws per 4'×8' sheet when attaching to wood studs 16" on center. Use 1-1/4" screws for 1/2" drywall over wood framing.

Can I install drywall vertically or horizontally?

Either orientation works, but horizontal installation often reduces the number of seams and creates stronger joints. Vertical may be easier for DIYers due to lighter weight per piece.

What tools do I need to cut drywall?

A utility knife, drywall saw, and measuring tape are essential. A drywall T-square helps make straight cuts, and a rasp smooths rough edges after cutting.