Buy the right number of sheets.
Enter your walls and see exactly how many sheets of drywall you need, plus the joint compound, tape, screws, and total cost, with a proper waste allowance built in.
The walls
What to know before you buy
Where the surface goes
Walls, ceiling, and cut waste
Materials scorecard
4 x 8 vs 4 x 12 for your area
Same drywall area, two sheet sizes, with your waste allowance and price. The row matching your choice is highlighted.
| Sheet size | Sheets | Mud | Tape | Cost |
|---|
Drywall, explained
Why You Need a Waste Allowance
You cannot use 100% of every sheet. Cuts around outlets, windows, doors, and corners create unusable scraps. A 10% waste factor is standard for simple rectangular rooms. Rooms with many openings, angled walls, or vaulted ceilings need 15% or even 20%. Better to buy a sheet extra than to need to drive back to the store mid-project.
Choosing Sheet Length
Longer sheets mean fewer butt joints to tape and mud, which makes for a cleaner finish. 12-foot sheets are preferred when handling space allows (two-car garage, large room with wide doorway). 8-foot sheets are easier to maneuver up stairs, through tight doorways, or for solo installation.
Standard vs Specialty Drywall
Standard 1/2-inch drywall fits most walls. 5/8-inch is required for fire-rated ceiling assemblies and garage walls adjacent to living spaces (most building codes). Moisture-resistant green board goes in bathrooms but is no longer recommended over backer board for tile in wet areas. Cement board is required behind ceramic tile in showers.
Calculating Mud, Tape, and Screws
For every 100 sq ft of drywall: about 5 lbs of joint compound, 50 ft of paper tape, and 60-70 drywall screws (1.25-inch). Sheets typically come in 4×8 (32 sq ft) and 4×12 (48 sq ft). Buy primer and a coat of paint separately, even one coat over fresh drywall mud needs proper coverage estimate.
Common questions
Does this include the ceiling?
No, enter only wall length and height. Calculate ceiling separately as a rectangle: ceiling area divided by sheet area, then add waste.
What about subtracting doors and windows?
For typical residential work, doors and windows are not subtracted because the cut-around scraps are usually unusable. The waste factor covers this. Only subtract for large openings (over 50 sq ft each).
Should I use 1/2-inch or 5/8-inch drywall?
1/2-inch fits most walls. 5/8-inch is required for fire-rated ceiling assemblies, garage walls adjoining living areas, and any code-mandated fire separation. Check local building code.
What if my walls are taller than 8 feet?
Use 9 or 10 ft sheets vertically, or run 8 ft sheets horizontally with a butt joint. Vertical installation with taller sheets gives a cleaner finish but is harder to install.
How many screws per sheet?
About 30-35 screws per 4×8 sheet (16-inch stud spacing). The standard is one screw every 12-16 inches on the perimeter and every 16 inches in the field.
Estimates for planning only. Real material counts depend on your layout, opening sizes, ceiling height, framing spacing and how much you cut. A 10% waste allowance suits simple rectangular rooms; plan 15% or more for complex layouts. Buy one extra sheet rather than stopping mid-hang.