Drywall Calculator
Estimate drywall (plasterboard) sheets and screws for walls and ceilings.
About the Drywall Calculator
Enter the total length of wall, the wall height, any ceiling area, the area of doors and windows, the sheet size and a waste allowance. The calculator gives the sheets to buy, the board area and an approximate screw count.
Add wall area (length × height, minus openings) and ceiling area, allow 10–15% for offcuts and divide by the sheet size. With framing at 16-inch (400 mm) centres, fastening works out to roughly one screw per square foot of board.
The formula
Sheets = ⌈(walls − openings + ceiling) × (1 + waste) ÷ sheet area⌉
Worked example
15 m of wall 2.4 m high, 4 m² of openings and a 14 m² ceiling, 1.2 × 2.4 m sheets, 10% waste
- Walls: 15 × 2.4 − 4 = 32 m²; plus ceiling = 46 m²
- With waste: 50.6 m² ÷ 2.88 m² = 17.6, so 18 sheets
- About 496 screws
Things to keep in mind
- Tape and joint compound depend on the product; follow the manufacturer's coverage.
Questions people ask
Which thickness?
12.5 mm (½ in) for walls; 15 mm (⅝ in) fire-rated board where codes require.
Hang walls or ceiling first?
Ceiling first, so wall sheets support its edges.
Longer sheets or standard?
Longer sheets mean fewer joints to tape, but are heavier to lift, especially on ceilings.