About this calculator
Sheets for a whole room, walls and ceiling, with doors and windows deducted, plus the screws, stud adhesive, base coat, topping, tape and cornice to finish them.
How it’s calculated
Wall area = perimeter × height − (doors × 1.9 m²) − (windows × 1.5 m²). Add the ceiling, add waste, and divide by the sheet area.
Walls are counted in 10 mm board and ceilings in 13 mm. Finishing rates used: about one 20 kg bag of base coat per 30 m² of board, one 15 L tub of topping per 40 m², and about 1.25 m of paper tape per m². Rates vary with the plasterer and the level of finish, so treat them as a guide.
Worked example
With these inputs:
- Room length
- 4.2 m
- Room width
- 3.6 m
- Wall height
- 2.4 m
- Doors
- 1
- Windows
- 2
- Include ceiling
- Yes
- Sheet size
- 2400 × 1200 mm
- Include cove cornice
- Yes
- Waste allowance
- 12%
the result is:
- Plasterboard sheets
- 19 sheets
- Wall area (net)
- 32.54 m²
- Ceiling area
- 15.12 m²
Tips from the trade
- Sheet the ceiling first, then the walls. Stagger end joints, and keep joints away from the corners of door and window openings, where they tend to crack.
- Wet areas need water-resistant board and a waterproofing membrane to AS 3740.
- Longer sheets mean fewer joints but need more hands.
- Don’t deduct small openings. The offcuts rarely get used.
Common questions
How many plasterboard sheets for a 3.6 × 3.6 m room?
With 2.4 m walls, one door, two windows and a ceiling: about 12 wall sheets and 6 ceiling sheets of 2400 × 1200, including waste.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and the NCC and Australian Standards before ordering.