Drywall Installation: How Many Sheets Do I Need?

How to Calculate Drywall for a Room

Measure each wall: multiply the length by the ceiling height to get the wall area in square feet. Add up all four walls. If you are covering the ceiling, multiply the room length by the room width and add that to the total.

Subtract door and window openings: a standard door opening is about 21 sq ft and a standard window is about 15 sq ft. Do not subtract for small openings like electrical boxes.

Divide the total area by the sheet size: a 4×8 sheet covers 32 sq ft and a 4×12 sheet covers 48 sq ft. Always round up to whole sheets and add 10-15% for waste, cuts, and mistakes.

Choosing the Right Sheet Size

4×8 sheets (32 sq ft) are the most common for DIY projects. They are lighter, easier to handle, and fit through standard doorways. Best for rooms with 8-foot ceilings.

4×12 sheets (48 sq ft) are preferred by professionals. They cover more area with fewer seams, which means less taping and a smoother finish. Essential for rooms with 9 or 10-foot ceilings.

For moisture-prone areas like bathrooms, use moisture-resistant (green board) drywall. For fire-rated walls like garages and utility rooms, use Type X (5/8-inch thick) drywall.

Accessories You Will Need

Joint compound (mud): plan for approximately one gallon per 100 square feet of drywall, covering three coats of finishing. A 4.5-gallon bucket handles about 450 sq ft.

Drywall tape: you need roughly 1 linear foot of tape per 1 square foot of drywall. Paper tape is the traditional choice; fibreglass mesh tape is easier for beginners but less suitable for inside corners.

Screws: use approximately 32 screws per 4×8 sheet (one every 12 inches on field studs, one every 8 inches on edges). Use 1-1/4 inch coarse-thread drywall screws for 1/2 inch board.

Corner bead: measure the total linear feet of outside corners. Metal corner bead is the most durable; paper-faced is easier to finish and resists cracking from settling.

Drywall Costs in 2026

Standard 1/2-inch 4×8 sheets cost $12-$18 each. Moisture-resistant green board costs $14-$22. Type X fire-rated costs $14-$20.

Professional drywall hanging runs $1.50-$3.00 per square foot. Finishing (taping, mudding, sanding) adds another $1.50-$2.50 per square foot.

For a typical 12×12 room with 8-foot ceilings, expect to need about 18 sheets for walls and ceiling, costing $200-$350 in materials or $1,500-$2,500 fully installed.