Drywall Calculator
Use this drywall calculator to find how many sheets you need for any room, plus the joint compound, tape, screws and cost. Enter your room size, subtract doors and windows, and compare every sheet size to cut waste and seams.
- Walls + ceiling
- Full material list
- Feet or meters
- Free, no sign-up
10% suits most rooms. Use 15% for many corners.
Prices (optional)
Please check the highlighted fields.
Drywall sheets needed
19
4×8 ft sheets, including 10% waste
Materials
Walls 416 ft² and ceiling 168 ft².
Compare sheet sizes
Larger sheets mean fewer seams to tape. Select a size to apply it.
| Sheet size | Sheets needed | Board area | Leftover | Screws |
|---|
Why this drywall calculator saves more than time
Most drywall calculators stop at the sheet count. This one gives you a complete shopping list and shows which sheet size wastes the least.
Complete shopping list
Sheets, joint compound, tape, screws and cost in one place, ready to copy for the store.
Sheet size comparison
See how 4×8, 4×10, 4×12 and longer sheets change the count, leftover and screws.
Walls and ceilings
Switch walls or the ceiling on and off, and multiply for identical rooms in one go.
Accurate openings
Doors and windows are deducted with editable sizes, so large patio doors are handled correctly.
Feet or meters
Use US sheet sizes in feet, or metric 1200 mm boards in square meters.
Private and shareable
Runs in your browser. Share a link with your contractor that reopens the exact room.
How to use the drywall calculator
Measure the room first, then follow these steps. Results update as you type.
- Choose feet or metersThe sheet sizes switch automatically to match your units.
- Enter the room sizeAdd the length, width and wall height. Then turn walls or the ceiling on or off.
- Subtract openingsEnter the number of doors and windows. Adjust their sizes if they are larger than standard.
- Pick a sheet size and wasteStart with 10% waste. Next, compare sheet sizes in the table below the result.
- Add prices and copy the listEnter local prices for a cost estimate, then copy the shopping list or share it.
How to calculate how much drywall you need
Drywall estimates start with surface area. First, find the wall area from the room perimeter and height. Next, add the ceiling. Then subtract doors and windows, add a waste allowance and divide by the area of one sheet.
Worked example: 14 × 12 ft bedroom
- Walls: 2 × (14 + 12) × 8
- 416 sq ft
- Ceiling: 14 × 12
- 168 sq ft
- Minus 1 door (21) and 2 windows (30)
- −51 sq ft
- Net area
- 533 sq ft
- Plus 10% waste ÷ 32 sq ft per 4×8 sheet
- 18.3
- Sheets to buy
- 19 sheets
For finishing, the same room needs about 4.8 gallons of joint compound, or two 4.5-gallon pails, plus around 197 feet of tape and roughly 600 screws.
Drywall sheet sizes and when to use them
Common sizes and the jobs they suit best.
| Sheet size | Area | Best for |
|---|---|---|
| 4 × 8 ft | 32 sq ft | DIY projects, small rooms, 8 ft walls |
| 4 × 10 ft | 40 sq ft | 9 to 10 ft walls hung vertically |
| 4 × 12 ft | 48 sq ft | Long walls and ceilings with fewer seams |
| 4 × 16 ft | 64 sq ft | Large commercial walls and ceilings |
| 1200 × 2400 mm | 2.88 m² | Standard metric board for 2.4 m walls |
| 1200 × 2700 mm | 3.24 m² | Rooms with 2.7 m ceilings |
How much joint compound, tape and screws you need
USG estimates about two 4.5-gallon pails of ready-mixed joint compound for every 1,000 square feet of wallboard. Industry guides also use roughly 370 linear feet of paper tape per 1,000 square feet. For screws, plan on about 32 per 4×8 sheet on walls framed 16 inches on center, which is close to one screw per square foot.
These are averages for a standard finish. A smooth Level 5 finish needs more compound, while rooms with many corners need more tape and corner bead. Once the walls are done, the paint calculator tells you how much primer and paint to buy.
Which drywall thickness should you use?
Half-inch board is the standard choice for interior walls. Five-eighths-inch board is common on ceilings and is required for many fire-rated walls. Thinner quarter-inch and three-eighths-inch sheets suit curved walls and covering old plaster.
Benefits of estimating drywall before you buy
A few minutes of planning saves money, trips and hours of extra taping.
Buy once. Avoid running out halfway through hanging and making a second store trip.
Cut waste. Compare sheet sizes to keep offcuts and disposal costs low.
Tape fewer seams. Larger sheets mean less mudding, sanding and drying time.
Budget accurately. Get a material cost before you request quotes from installers.
Plan the whole room. Pair it with the square footage calculator and the tile calculator.
Share with your crew. Send one link so everyone orders the same materials.
Drywall calculator FAQs
Quick answers for homeowners, DIYers and contractors.
With 8-foot walls, a 12 x 12 room has 384 sq ft of wall and 144 sq ft of ceiling. Add 10% waste and you get about 581 sq ft, or 19 sheets of 4x8 drywall before subtracting doors and windows.
Multiply the room perimeter by the wall height to get the wall area, then add length times width for the ceiling. Subtract about 21 sq ft for each door and 15 sq ft for each window.
USG estimates about two 4.5-gallon pails of ready-mixed joint compound per 1,000 sq ft of drywall. That is roughly 0.9 gallons per 100 sq ft for a standard finish.
Plan on about 370 linear feet of tape for every 1,000 sq ft of drywall. A 500-foot roll therefore covers around 1,350 sq ft.
Use about 32 screws for a 4x8 sheet on walls framed 16 inches on center, which is close to one screw per square foot. Ceilings often need tighter spacing, so check your local code.
Larger sheets such as 4x12 mean fewer seams and less taping, so they suit long walls and ceilings. However, 4x8 sheets are lighter and easier to carry, which makes them better for DIY work and small rooms.
Add 10% for most rooms. Use 15% for rooms with many corners, openings or angled ceilings, and about 5% for long, simple walls.
Half-inch drywall is standard for interior walls. Five-eighths-inch board is common on ceilings and fire-rated walls, while quarter-inch and three-eighths-inch sheets suit curves and covering old plaster.
Hang it right with the right amount
Measure once, buy once. This drywall calculator gives you sheets, finishing supplies and cost in a single shopping list you can take to the store.
Estimates use average coverage rates. Actual compound, tape and screw use depends on the product, framing, finish level and installer, so check product labels and local building codes.