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Calculate drywall sheets, joint compound, tape, and screws needed for your project. Get accurate material estimates with waste calculation and complete cost breakdown.
Tip: (2 × length + 2 × width) × height
Tip: length × width
Subtracts ~21 sq ft per door
Subtracts ~15 sq ft per window
Horizontal reduces seams on walls
4x8 (32 sq ft each)
Subtract door (21 sq ft) and window (15 sq ft) areas. Add 5-15% waste for cuts and mistakes.
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Drywall, also known as sheetrock, gypsum board, or wallboard, is a panel made of calcium sulfate dihydrate (gypsum) pressed between two thick sheets of paper. It's the most common material for interior walls and ceilings in modern construction.
Standard drywall comes in 4-foot-wide panels in various lengths (8, 10, or 12 feet) and thicknesses (1/4", 3/8", 1/2", 5/8"). The most common size for residential walls is 1/2" thick, 4' × 8' sheets.
Common Drywall Types:
Follow these steps to calculate drywall:
Room: 12' × 14', 8' high, 2 doors
Walls = ((12+14)×2) × 8 = 416 sq ft
Ceiling = 12 × 14 = 168 sq ft
Doors = 2 × 21 = -42 sq ft
Net = 416 + 168 - 42 = 542 sq ft
Waste (10%) = 542 × 1.10 = 596 sq ft
Sheets (32 sq ft) = 19 sheets
At $12/sheet: 19 × $12 = $228
Also called mud, used to fill seams and cover screw holes. You'll need about 1 gallon per 100 sq ft for three coats.
Types needed:
Drywall Tape
Paper or fiberglass mesh, ~1 roll per 250 linear feet of seams
Drywall Screws
1-1/4" for 1/2" drywall, ~1000 per 500 sq ft
Corner Bead
Metal or vinyl for outside corners
The industry recognizes 5 levels of drywall finish, from basic to smooth:
| Level | Description | Use Case |
|---|---|---|
| Level 0 | No taping or finishing | Temporary construction |
| Level 1 | Tape embedded in compound | Above ceilings, attics |
| Level 2 | Tape + one coat over fasteners | Garages, warehouse |
| Level 3 | Tape + two coats compound | Heavy texture finishes |
| Level 4 | Tape + three coats | Flat paint, light texture |
| Level 5 | Level 4 + skim coat entire surface | Glossy paint, critical lighting |
For a 12×12 room with 8-foot ceilings, you need approximately 15-16 sheets of 4×8 drywall (14 for walls + 5 for ceiling, minus openings, plus 10% waste).
Horizontal (perpendicular to studs) is recommended for walls as it creates fewer seams and provides better strength. Vertical works for closets or when you need full-height coverage with 8-foot sheets.
Add 5-10% waste for simple rectangular rooms, 10-15% for rooms with many corners, angles, or openings. Professional installers typically add 10% as standard practice.
1/2" is standard for walls and ceilings with 16" stud spacing. Use 5/8" for ceilings with 24" spacing, fire-rated walls, or better soundproofing. 1/4" and 3/8" are for curved walls or repairs.
Plan for 1 gallon per 100 square feet for three coats. A typical 12×12 room (about 600 sq ft) needs 6 gallons or approximately 4-5 bags of compound (mix of all-purpose and topping).
All-purpose compound is stronger and used for taping and first coats. Topping compound is softer, easier to sand, and used for final smooth coats. Many pros use both for best results.
Yes, all seams must be taped to prevent cracking. Use paper tape with compound for flat seams, or self-adhesive fiberglass mesh for repairs. Corners use paper tape or metal/vinyl corner bead.
Use approximately 32 screws per 4×8 sheet: every 12 inches on walls, every 12 inches along edges and 16 inches in the field on ceilings. Space screws 3/8" from edges.
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