Loona Construction Calculators
Sheeting a room with plasterboard or drywall? Enter the room dimensions and the calculator works out the wall area (plus ceiling, if you are boarding it) and how many standard sheets you need — 1200 × 2400 mm sheets in metric, 4 × 8 ft sheets in imperial.
Work out the wall area (perimeter × height), add the ceiling if boarding it, add 10% for cuts, and divide by the sheet area — 2.88 m² for a 1200 × 2400 mm sheet or 32 ft² for a 4 × 8 ft sheet.
No. The board around doors and windows is cut from full sheets and the offcuts are rarely reusable elsewhere; the waste allowance covers it. Subtracting openings usually leaves you a sheet short.
1200 × 2400 mm (metric) and 4 × 8 ft (imperial) are the standard, cheapest sheets and fit standard stud spacing. Longer 2700 mm / 12 ft sheets suit tall rooms and reduce joints, but are harder to handle alone.
Area to board = 2 × (Length + Width) × Height, plus Length × Width if the ceiling is included
Sheets = Area × (1 + Waste %) ÷ Sheet area, rounded up
Sheet areas: 1200 × 2400 mm = 2.88 m²; 1200 × 2700 mm = 3.24 m²; 4 × 8 ft = 32 ft² (2.97 m²); 4 × 12 ft = 48 ft² (4.46 m²).
12.5 mm (½ in) is standard for walls and ceilings. Use moisture-resistant board in bathrooms, fire-rated board where regulations require it (garages, party walls), and 9.5 mm (⅜ in) only for curved work.
10% for rectangular rooms. Stairwells, sloped ceilings and rooms with many openings justify 15%. Sheets damaged in transport are replaced by the merchant — check them on delivery.
Yes — switch to Imperial for feet and 4 × 8 or 4 × 12 ft sheets. Because metric and imperial sheet sizes differ slightly, the count can differ by a sheet for the same room; buy for the sheets you will actually purchase.
Add this calculator to your own website or blog — it is completely free, needs no sign-up, and always shows the latest version. Copy the code below and paste it into your page where you want the calculator to appear. Keeping the small “Powered by Loona Automation” credit line under the embed helps keep this tool free — but you are free to style or remove it; the tool works either way.