How to Calculate Drywall
Wall Area = 2 × (Length + Width) × Height Net Area = Wall Area + Ceiling Area − Openings Sheets = ⌈Net Area ÷ 32⌉ (4×8 sheet = 32 sq ft)
Drywall Thickness Guide
| Thickness | Use |
|---|---|
| ¼" | Curved surfaces, over existing drywall |
| ⅜" | Repairs, garage ceilings (older homes) |
| ½" | Standard walls and ceilings (most common) |
| ⅝" | Fire-rated walls, soundproofing, commercial |
Don't Forget Supplies
This free tool gives you the sheet count — but budget for supplies too: joint compound (1 gallon per 100 sq ft), drywall tape, corner bead, screws (1 lb per 500 sq ft), and primer. For ceilings, use ⅝" sag-resistant drywall — standard ½" can sag between joists over time.
Frequently Asked Questions
How many sheets of drywall do I need for a 12×12 room?+
A 12×12 room with 8-foot ceilings has approximately 384 sq ft of wall area. Minus 2 doors (42 sq ft), you need about 342 sq ft of drywall, which equals 11 sheets of 4×8 drywall (32 sq ft each) plus waste.
What thickness drywall should I use for walls?+
½-inch drywall is standard for most interior walls and ceilings. Use ⅝-inch for fire-rated walls (garages, between floors), soundproofing, and commercial applications. ¼-inch is for curved surfaces only.
How much does drywall cost per sheet?+
Standard ½-inch 4×8 drywall sheets cost $12–$20 each at home centers depending on type and location. Moisture-resistant (green board) and fire-rated (type X) varieties cost $15–$25 per sheet.
Do I need special drywall for a bathroom?+
Yes. Use moisture-resistant drywall (greenboard) in bathrooms — but not in shower or tub areas, which require cement board. Paperless drywall or glass-mat drywall is even more mold-resistant in humid areas.