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Drywall & Sheetrock Calculator

Estimate drywall panel sheets, joint compound mud, screws, and tape for walls and ceilings.

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Reviewed by Tariq Al-Mansoor, Senior Construction Estimator & QS (15+ yrs exp) Verified against ISO 80000 & ASTM building measurement standards

Your estimate

Enter measurements, then calculate.

Planning estimate only. Confirm packaging, coverage, site conditions, and local building requirements before purchasing.

Measurement Schematic Visual guide for dimensions & layout

How to measure

Measure wall lengths and heights, multiplying to find gross square meters / square feet.
Measure ceiling length and width to calculate ceiling drywall area.
Subtract large openings (doors and picture windows) exceeding 3.5 m² (40 sq ft).
Select drywall sheet size (standard 4×8 ft / 1.2×2.4 m or 4×12 ft / 1.2×3.0 m).

Input guide

Enter net wall/room length and height in meters or feet.
Input drywall sheet length and width (default: 2.4 m × 1.2 m / 8 ft × 4 ft).
Apply a 10% waste allowance for cut offcuts and framing alignment.
Enter price per sheet to calculate total drywall board material costs.

Formula

Drywall Sheets = Ceiling( (Net Area × (1 + Waste Allowance)) ÷ Sheet Area )

Gross wall and ceiling surfaces are combined and adjusted for major architectural openings.

The net area is multiplied by the waste allowance and divided by individual drywall panel area.

Consumables are derived: approx. 32 screws per sheet and 2.8 kg joint compound per sheet.

Worked example: Basement room drywall installation

A room with 6.0 m wall run and 2.7 m height produces 16.2 m² of wall area.
Subtracting 2.0 m² for a doorway leaves 14.2 m² net area.
Standard 1.2 m × 2.4 m sheets have an area of 2.88 m² per panel.
With 10% waste: (14.2 × 1.10) ÷ 2.88 = 5.42 sheets, rounded up to 6 sheets.

At 15 USD per sheet, estimated cost is 90 USD for 6 sheets (~192 screws & 17 kg joint compound).

Buying advice

Use 5/8 in (16 mm) Type X fire-rated drywall for garage walls and utility ceilings.
Use moisture-resistant green board or cement backer board for bathrooms and laundry areas.
Choose longer 12 ft (3.6 m) boards for large rooms to eliminate weak mid-wall butt joints.

Common mistakes

Aligning sheet seams directly with door and window corners where vibration creates cracks.
Fastening standard gypsum board inside tiled shower enclosures without waterproof backer boards.
Over-driving drywall screws so deep that they tear the paper face, ruining holding power.
Hanging wall drywall before ceiling drywall is completed.

Framing layout and sheet orientation

Drywall panels are traditionally hung horizontally on walls to create fewer linear feet of seams and bridge framing irregularities across studs spaced 16 in (40 cm) or 24 in (60 cm) on-center.

Stagger horizontal butt joints by at least 16 inches between courses, and avoid aligning seams directly with the edges of door and window frames where cracking is most common.

Drywall fasteners and joint compound checklist

Standard 4×8 ft sheets require approximately 32 drywall screws per sheet (spaced 12 in on walls, 8 in on ceilings).
Joint compound consumption averages 1 gal (3.8 L / 5.5 kg) of pre-mixed mud per 100–120 sq ft of drywall surface for 3-coat taping.
Budget 100 ft (30 m) of paper tape or fiberglass mesh tape per 4–5 drywall sheets.
Order metal or vinyl corner beads for all outside 90° corners, counting length in full 8 ft or 10 ft sticks.
Use 5/8 in (16 mm) Type X fire-rated board for garage-to-house separation walls and fire-rated ceilings.

Moisture resistance and structural limits

Standard gypsum board must not be installed in direct wet areas such as tiled shower enclosures. Use cement backer board or waterproof foam panels in wet zones.

This calculator estimates surface panels and consumables. It does not calculate framing timber load, resilient acoustic channels, or fire-rating assembly ratings.

Frequently asked questions

How many screws do I need per sheet of drywall?

Budget approximately 32 screws per 4×8 ft sheet on walls, spaced 12 inches apart.

How much joint compound is needed per sheet?

Plan for approx. 1 gallon (3.8 L / 5.5 kg) of ready-mixed compound per 4 sheets of drywall.

Should drywall be hung horizontally or vertically?

Hanging horizontally on walls creates fewer joints and bridges stud imperfections.

What is the standard drywall thickness for interior walls?

1/2 inch (12.7 mm) is standard for residential interior walls.