Drywall Calculator
Find how many sheets of drywall you need for the walls and ceiling of a room, with waste included.
Free · No sign-up · Runs in your browser · Last reviewed November 2026
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About the Drywall Calculator
Drywall is sold in sheets, most often 4 by 8 feet (32 square feet) or 4 by 12 feet (48 square feet). This drywall calculator adds up the wall and ceiling area, subtracts doors and windows, divides by the sheet size and adds 10% for cuts and waste. You will also need joint compound, tape and screws, which depend on the number of sheets.
How to use it
- Enter the room length, width and wall height.
- Choose whether to include the ceiling and the sheet size, and enter the area of doors and windows.
- Press Calculate drywall to see the number of sheets and cost.
Drywall formula
Sheets = (wall area + ceiling area − openings) ÷ sheet area × 1.10. A 14 × 12 ft room with 8 ft walls has 416 sq ft of wall, minus 60 for openings, plus 168 of ceiling: 524 sq ft, which is about 19 sheets of 4 × 8 once you add 10% waste.
Common drywall thicknesses
| Thickness | Typical use |
|---|---|
| 1/2 inch | Standard walls and ceilings |
| 5/8 inch | Fire-rated walls, ceilings with wider joist spacing |
| 1/4 inch | Curved surfaces and overlays |
Tips
- Longer 12-foot sheets mean fewer seams on large walls.
- Hang ceilings first, then walls.
- Plan about 32 screws per 4 by 8 sheet.
Drywall planning tips for a second room
A 12 × 10 ft room with 8 ft walls has 352 sq ft of wall and 120 sq ft of ceiling. Subtract 40 sq ft for a door and a window and you get 432 sq ft. Using 4 × 12 ft sheets (48 sq ft) that is exactly 9 sheets, and with 10% waste about 9.9, so order 10.
Practical tips
- Choose the right sheet length. 12 ft sheets reduce seams on long walls but are heavy and hard to carry through tight halls. Many DIYers prefer 4 × 8.
- Use moisture-resistant board in wet areas. Bathrooms and laundry rooms usually call for water-resistant or cement board behind tile.
- Do not skimp on screws and compound. A typical room needs several buckets and rolls of tape, which are separate costs.
- Stagger joints. End seams that line up from row to row tend to crack.
Drywall is often installed after wall cavities are filled; plan your batts with the insulation calculator first.
Frequently asked questions
How many sheets of drywall do I need for a room?
Calculate wall and ceiling area, divide by 32 for 4 by 8 sheets and add 10%. A 12 by 12 room with 8 ft walls and a ceiling needs about 19 sheets of 4 by 8.
How much does a sheet of drywall cost?
Standard 1/2 inch 4 by 8 sheets typically cost roughly $12 to $20, varying by region.
Should I subtract windows and doors?
Yes for large openings, but small openings are often ignored because the waste allowance covers them.
How much joint compound do I need?
Roughly one 4.5 gallon bucket for every 400 to 500 square feet of drywall, depending on finish level.
Is 4 by 12 better than 4 by 8?
On long walls, fewer joints mean less finishing, but the sheets are heavier and harder to carry.
How many pounds does a sheet of drywall weigh?
A 4 by 8 ft sheet of 1/2 inch drywall weighs roughly 50 to 60 pounds, and 5/8 inch sheets weigh more. Larger 4 by 12 ft sheets are proportionally heavier.
Should I hang drywall horizontally or vertically?
Horizontal hanging is common on 8 ft walls because it shortens seams and places them at a comfortable height for finishing. Ceilings are usually hung first, perpendicular to the joists.
Last reviewed: November 2026.