What Is Drywall (Sheetrock)?
Drywall — also known as sheetrock, plasterboard, wallboard, gypsum board, or gypsum panel — is the standard material for finishing interior walls and ceilings in modern construction. A drywall sheet consists of a gypsum (calcium sulfate dihydrate, Ca₂SO₄·2H₂O) core pressed between two thick sheets of paper. Its popularity soared during World War II when traditional plastering was too costly and time-consuming, and it remains the go-to choice today because it is fast to install, easy to repair, and widely available.
Types of Drywall Sheets
- Regular drywall — White paper facing, available in many thicknesses from ¼ in (6.5 mm) to ¾ in (20 mm). Best for standard interior walls in dry areas.
- Greenboard drywall — Green paper facing treated with water-repellent molecules. Ideal for kitchens and other humid rooms (not fully waterproof).
- Blueboard drywall — Blue paper facing, moisture- and mold-resistant. Costs more than greenboard but offers better protection.
- Soundproof drywall — Contains damping polymers and extra mass layers to reduce sound transmission between rooms.
- Type X drywall — Fire-resistant. Glass fibers embedded in the core prevent cracking as water evaporates during a fire.
- Type C drywall — Enhanced fire resistance. Glass fibers plus vermiculite that expands to seal cracks under high heat.
- Cement board — Not drywall per se, but a common alternative for wet areas such as bathrooms and tile substrates.
Drywall Sizes and Thickness
Standard drywall sheets come in the following sizes:
- Imperial: 4×8 ft (32 sq ft), 4×10 ft (40 sq ft), 4×12 ft (48 sq ft)
- Metric: 1200×2400 mm (2.88 m²), 1200×3000 mm (3.60 m²), 1200×3600 mm (4.32 m²)
Common thicknesses: ¼ in (6.35 mm) for curved surfaces, ⅜ in (9.5 mm) for repairs, ½ in (12.7 mm) for most walls and ceilings, ⅝ in (15.9 mm) for fire-rated or soundproofing applications.
How Much Drywall Do I Need?
Our drywall estimator follows these steps:
- Wall area = 2 × (room length × ceiling height + room width × ceiling height)
- Ceiling area = room length × room width (if drywalling the ceiling too)
- Deductions — Standard door: 3.5 ft × 7 ft = 24.5 sq ft (0.9 m × 2.1 m ≈ 1.89 m²). Standard window: 3 ft × 4 ft = 12 sq ft (0.9 m × 1.2 m ≈ 1.08 m²)
- Net area = wall area + ceiling area − doors − windows
- Sheets needed = ⌈net area ÷ sheet area⌉ (rounded up)
- Sheets to buy = ⌈sheets needed × (1 + waste %)⌉ — the waste factor (default 10 %) accounts for cuts, mistakes, and odd angles
Drywall Cost Calculator
Enter the price per sheet in your local currency to get the total material cost. The calculator supports 20 world currencies including USD and RUB. Note that this estimate covers sheets only — add labor, joint compound, tape, screws, and primer for a complete project budget.
Tips for Drywalling
- Do not use standard drywall in kitchens, bathrooms, or any area exposed to moisture — use greenboard, blueboard, or cement board instead.
- Consider fire-resistant Type X or Type C drywall for the wall separating your house from the garage.
- Buy 10–15 % extra to account for waste from cuts around doors, windows, outlets, and sloped ceilings.
- For ceilings, use ⅝ in (15.9 mm) drywall or hang boards perpendicular to joists to reduce sagging.
- Score-and-snap cutting is fast and clean; use a utility knife and a T-square for straight lines.