Drywall Calculator — Sheets, Cost & Materials
Estimate drywall sheets, joint compound, tape, and screws for walls and ceilings. Enter the room dimensions, deduct doors and windows, and get instant material counts plus an installed cost estimate.
Drywall Calculator
Drywall Sheet Sizes
| Sheet Size | Metric | Coverage | Best For |
|---|---|---|---|
| 4 × 8 ft | 1219 × 2438 mm | 32 sq ft (2.97 m²) | Standard rooms, easy to handle |
| 4 × 10 ft | 1219 × 3048 mm | 40 sq ft (3.72 m²) | Tall walls, fewer joints |
| 4 × 12 ft | 1219 × 3658 mm | 48 sq ft (4.46 m²) | Long walls, professional jobs |
| 1200 × 2400 mm (EU/AU) | — | 2.88 m² (31 sq ft) | Standard metric size |
| 1200 × 3000 mm (EU/AU) | — | 3.6 m² (38.7 sq ft) | Ceilings, tall walls |
How to Measure for Drywall
- Measure each wall: length × ceiling height = wall area in sq ft (or m²).
- Add up all walls in the room. For a rectangular room: 2 × (length + width) × height.
- Add ceiling area (length × width) if you’re drywalling the ceiling too.
- Subtract openings: standard door = 21 sq ft (1.95 m²), standard window = 15 sq ft (1.39 m²). Don’t deduct openings smaller than 5 sq ft.
- Add 10–15% waste for cuts, bad sheets, and corners.
- Divide by sheet coverage to get the number of sheets.
Imperial example: 12×13 ft room, 8 ft ceiling, 2 doors, 2 windows, ceiling drywalled too. Walls: 2×(12+13)×8 = 400 sq ft. Ceiling: 156 sq ft. Deductions: 72 sq ft. Net: 484 sq ft × 1.10 = 533 sq ft ÷ 32 = 17 sheets (4×8).
Metric example: 3.7×4 m room, 2.4 m ceiling, 2 doors, 2 windows. Walls: 2×(3.7+4)×2.4 = 36.96 m². With ceiling: 51.76 m². Deductions: 6.68 m². Net: 45.08 m² × 1.10 = 49.6 m² ÷ 2.88 = 18 sheets (1200×2400 mm).
Drywall Types
- Regular (white): 1/2 in (12.7 mm) for walls, 5/8 in (16 mm) for ceilings. Standard rooms.
- Moisture-resistant (greenboard): bathrooms, kitchens, laundry rooms. Not for direct water contact.
- Cement board: behind tile in showers and tub surrounds — fully waterproof.
- Fire-resistant (Type X): 5/8 in (16 mm). Required by code in garages, attached residential, and between living units.
- Soundproof / mold-resistant: upgraded specialty boards. ~2–3× the cost of regular.
Drywall Installation Tips
- Hang horizontally on framed walls for stronger seams and easier finishing (one continuous taped joint at 4 ft height).
- Stagger joints — never align butt joints between adjacent sheets; they create visible cracks over time.
- Score and snap with a utility knife on the front face, snap back, then cut the paper backing.
- Screws every 12 in (30 cm) on field, 8 in (20 cm) on edges. Use #6 × 1¼″ coarse-thread for wood studs.
- Tape and three coats of compound: tape coat (thin) → second coat (wider) → finish coat (sand smooth).
Frequently Asked Questions
How many sheets of drywall for a 12×12 room?
A 12×12 ft room with 8 ft ceilings has a perimeter of 48 ft × 8 = 384 sq ft of wall. After deducting one door (21 sq ft) and one window (15 sq ft) = 348 sq ft. With 10% waste = 383 sq ft. At 32 sq ft per 4×8 sheet = 12 sheets. Add 5 more for the ceiling (144 sq ft).
How much does drywall cost?
$10–$15 per 4×8 ft sheet (1/2 in standard). Moisture-resistant (greenboard) runs $13–$18, fire-resistant (Type X) $14–$20. Add ~$50 for joint compound + tape + screws for an average room.
What thickness drywall for walls vs ceiling?
Walls: 1/2 in (12.7 mm) standard. Ceilings: 5/8 in (16 mm) recommended to resist sagging and meet most building codes. For garages and between living spaces, use 5/8 in Type X (fire-rated).
How much joint compound do I need?
Approximately 1 gallon per 100 sq ft (3.8 L per 9.3 m²) of drywall, plus 1 gallon per 50 sq ft if you’re skim-coating. A 5-gallon (19 L) bucket covers about 500 sq ft (46 m²) for standard taping and finishing.
Related Calculators
- Tile Calculator — for floors, walls, and backsplash
- Wallpaper Calculator — finishing the new drywall with wallpaper?
- Carpet Calculator — new carpet over fresh drywall?
- Paint Calculator — painting the new drywall
- Cubic Yards Calculator — generic volume
- Area Unit Converter — convert between square feet, square meters, acres, hectares
- All Construction Calculators
Coverage assumes standard 4×8 ft sheets at 32 sq ft each. Joint compound, tape, and screw quantities are typical industry estimates. Prices are 2026 US national averages and will vary by region. For commercial or fire-rated assemblies, follow local building codes.
