How many plasterboard sheets do I need?
The calculator works out the wall area (perimeter × height), deducts openings (about 1.9m² per door and 1.4m² per window), adds the ceiling if selected, then divides by the sheet size with 10% added for cuts and offcuts.
Plasterboard sheet sizes and coverage
| Sheet size | Coverage | Sheets per 10m² |
|---|---|---|
| 2400 × 1200mm | 2.88 m² | 3.5 (4 with cuts) |
| 2400 × 900mm | 2.16 m² | 4.6 (6 with cuts) |
| 1800 × 900mm | 1.62 m² | 6.2 (7 with cuts) |
| 2700 × 1200mm | 3.24 m² | 3.1 (4 with cuts) |
Fixings and finishing materials
- Drywall screws: about 12.5 per m² (300mm centres on walls, 230mm on ceilings), 10–15mm in from the edges. Sold in boxes of 1,000.
- Dot & dab adhesive: about 5m² per 25kg bag. Apply dabs roughly 50–75mm wide and 250mm long, at about 300mm centres, plus a continuous line around the perimeter and openings.
- Joint tape: about 1.3m per m² of board, covering all joints and internal corners.
- Jointing compound: about 0.5kg per m² for a full tape-and-joint finish (bedding, second coat and finishing coat).
- Skim plaster: a 25kg bag of finishing plaster covers about 10m² at 2mm.
Ceilings are always screw-fixed, even when walls are dot and dabbed. Stagger the board joints, fix ceiling sheets across the joists, and leave a small gap at the floor so boards don't wick up moisture.
Worked example: boarding a 4m × 3m room
The walls are 2 × (4 + 3) × 2.4m = 33.6m². Less about 1.9m² for the door and 1.4m² for the window, that's 30.3m². With 10% for cuts, 30.3 × 1.1 ÷ 2.88 = 11.6, so 12 sheets of 2400 × 1200mm. Screwed to studs, that's about 420 drywall screws (one box of 1,000), 40m of joint tape and roughly 15kg of jointing compound. Add the 12m² ceiling and it rises to 17 sheets.
Dot and dabbing the same walls onto brick or block instead takes about 7 × 25kg bags of adhesive, more if the walls are very uneven.
Which plasterboard?
- Standard (usually grey or white face): most walls and ceilings.
- Moisture-resistant (green): bathrooms, kitchens and utility rooms. In showers, use a tile backer board with a tanking system instead.
- Acoustic (blue) and fire-rated (pink): denser boards for quieter rooms and walls with fire resistance requirements, such as garages and loft escape routes.
- Thermal laminate: board with insulation bonded to the back, for cold external walls.
Handling and fitting tips
A full 2400 × 1200mm sheet of 12.5mm board weighs over 20kg and is awkward to carry, so get help, especially for ceilings, where hiring a board lifter makes one-person fixing possible. Cut by scoring the face with a sharp knife, snapping the board over a straight edge and cutting the back paper. Drive screws so the heads sit just below the surface without tearing the paper, and keep joints away from the corners of door and window openings, where cracks tend to start.
Common mistakes
- Not enough fixings. Boards with too few screws flex and crack at the joints. Keep to 300mm centres on walls and 230mm on ceilings.
- Joints that don't land on timber. Every board edge must sit on a stud, joist or noggin. Plan the layout before cutting.
- Taping square-edged board. Tape and joint suits tapered-edge boards. Square edges are usually skimmed.
For cracked joints and how to prevent them, see our self-levelling and plasterboard guide. The frame comes from the stud wall calculator, and the finish from the plaster calculator.