Drywall Calculator — How Many Sheets of Drywall You Need

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Adjust the inputs to see your result.

How the math works

Drywall is sold by the sheet, but you estimate it by area. The calculator works out the surface area you're covering, adds a waste allowance for cutouts and mistakes, then divides by the area of one sheet and rounds up. From the sheet count it derives everything else you buy in the same trip: screws, joint compound, tape, and corner bead.

Wall area is the room perimeter times the ceiling height — 2 × (length + width) × height. If you're hanging the ceiling too, add length × width. A 4×8 sheet covers 32 ft²; a 4×10 covers 40; a 4×12 covers 48. Prefer to skip the geometry? Switch to square-footage mode and type the total directly.

Screws, compound, tape, and bead

A 4×8 sheet takes about 32 screws — every 12 inches in the field, 8 on the edges — and a 1 lb box of 1-5/8-inch screws holds roughly 320, so one pound hangs about ten sheets. Taping and three coats of all-purpose compound use about 0.053 lb per square foot, so a 4.5-gallon box (61.7 lb) covers around 475 ft². Joint tape runs about 0.4 linear feet per square foot of board. Corner bead is sold in 8 ft sticks, one per eight feet of outside corner.

Common mistakes

Not adding waste. Cutouts around doors, windows, and outlets leave unusable offcuts. 10% is standard; cut-up rooms want 15%.
Forgetting the ceiling. The ceiling is often the largest single plane in the room — check the box if you're hanging it.
Defaulting to 4×8 on long walls. Longer sheets and 54-inch board cut the number of butt joints you have to tape and sand.
Buying exactly the count. Order one extra sheet. A damaged corner or a blown measurement shouldn't mean a second trip to the store.

When this calculator is the wrong tool

This estimates flat walls and ceilings for a rectangular room. For vaulted or sloped ceilings, curved walls, soffits and tray ceilings, or fire- and water-rated assemblies with specific board types and layer counts, take off each plane individually and follow the assembly's listing. This tool covers standard single-layer 1/2-inch board.

Sheet coverage is plain geometry; screw, compound, and tape rates are from USG / National Gypsum public installation guides.

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FAQ

Questions, answered

How many sheets of drywall do I need for a 12×12 room?

A 12×12 room with 8 ft ceilings has 384 ft² of wall (2 × (12+12) × 8). With a standard 10% waste allowance that's about 14 sheets of 4×8 drywall for the walls. Add the ceiling (144 ft²) and it rises to roughly 19 sheets.

How do I calculate drywall square footage?

For walls, multiply the room perimeter by the ceiling height: 2 × (length + width) × height. Add length × width if you're drywalling the ceiling too. Then divide by the area of one sheet — a 4×8 sheet is 32 ft², a 4×12 is 48 ft² — and round up after adding 10% for waste.

How many screws per sheet of drywall?

About 32 screws per 4×8 sheet — roughly every 12 inches on studs in the field and 8 inches on the edges. A 1 lb box of 1-5/8-inch coarse-thread screws holds about 320, so one pound covers around 10 sheets.

How much joint compound and tape will I need?

Tape plus three coats uses about 0.053 lb of compound per square foot of board, so a 4.5-gallon (61.7 lb) box covers roughly 475 ft². Joint tape runs about 0.4 linear feet per square foot of board, so a 250 ft roll covers around 625 ft².

Should I use 4×8 or longer drywall sheets?

Longer sheets (4×10 or 4×12) mean fewer butt joints to tape and a flatter wall, which is why pros prefer them — but they're heavier and harder to maneuver in tight spaces and up stairs. For tall or long walls, 54-inch-wide board can eliminate a row of horizontal seams entirely.