Free Drywall Calculator
Measure your walls or your whole room, pick a sheet size, and get the sheet count plus screws, joint compound, and tape estimates, all calculated in your browser.
This free drywall calculator turns your wall and ceiling measurements into sheet counts for 4x8, 4x10, and 4x12 drywall, adds a waste factor, and estimates the screws, joint compound, and seam tape the job needs.
Add each wall you plan to drywall.
Estimates use standard rules of thumb: one screw per square foot, one gallon of joint compound per 100 square feet, one 250-ft tape roll per 400 square feet. See Terms of Use.
How to estimate drywall for a room
Start by measuring every wall you plan to cover. For each wall, multiply its length by its height to get its square footage, then add the walls together. For the ceiling, multiply the room length by the room width and add that in. Subtract the openings: 21 square feet per standard door, about 12 per average window. What remains is your net drywall area.
Next, divide that area by the size of the sheet you plan to buy. A 4x8 sheet covers 32 square feet, a 4x10 covers 40, and a 4x12 covers 48. Round up to the next whole sheet, then add your waste factor. Ten percent is standard for simple rooms. Use 15 percent if the room has many corners, angles, or openings that force extra cuts.
Bigger sheets mean fewer seams, and fewer seams mean less taping and mudding. A 12-foot sheet spans most residential walls in one piece, but 4x12s are heavy and awkward on ceilings, so many DIYers stick with 4x8s for overhead work. Match the sheet length to your longest wall run so no butt joint lands mid-wall.
Finally, estimate the fasteners and finish materials. Plan on about one screw per square foot of drywall, one gallon of joint compound per 100 square feet for three coats, and one 250-foot roll of joint tape for every 400 square feet. Buy screws in bulk boxes and compound in 4.5-gallon buckets: it costs less than small tubs, and running out mid-coat is the fastest way to turn a weekend project into a two-week one.
Drywall calculator questions
How many sheets of drywall do I need for a 12x12 room?
A 12 by 12 foot room with 8-foot ceilings has 384 square feet of wall area. Add the 144-square-foot ceiling and you get 528 square feet. With 4x8 sheets (32 square feet each), that is 16.5 sheets, so 17 before waste, and 19 sheets with a 10 percent waste factor.
Should I buy 4x8, 4x10, or 4x12 drywall sheets?
Larger sheets cover more area with fewer seams, which means less taping and finishing. Use 4x12 sheets on long straight walls to avoid butt joints. They are heavy, so 4x8 or 4x10 sheets are easier to handle on ceilings and in tight rooms. Match the sheet length to your longest wall run when you can.
How many screws and how much joint compound does drywall need?
Plan on about one drywall screw per square foot of drywall, spaced 12 inches apart on edges and 16 inches in the field. For joint compound, budget one gallon per 100 square feet for three coats, and one 250-foot roll of joint tape per 400 square feet.
Do I hang drywall horizontally or vertically?
Hang sheets horizontally on walls 8 feet or shorter: two 4-foot rows, staggered, which cuts the seam count roughly in half. On walls taller than 8 feet, hang vertically to avoid a long horizontal butt seam. On ceilings, run sheets perpendicular to the joists, and consider renting a drywall lift for 4x12s.