How many plasterboard sheets do I need?
27 September 2026 · 4 min read · by Rodney Lee
Plasterboard is cheap but heavy and awkward to store, so ordering roughly the right amount matters. The maths is simpler than it looks: everything comes down to square metres.
Board sizes and coverage
- 2400 × 1200 mm board (the standard size) covers 2.88 m².
- 1800 × 900 mm (handy in lofts and small rooms) covers 1.62 m².
- Wall thickness: 9.5 mm for ceilings, 12.5 mm for walls is the usual choice.
Measure the job
For walls: perimeter × height. For a 4 m × 4 m room with a 2.4 m ceiling that's 38.4 m² of wall. For the ceiling: length × width, so another 16 m². Total ≈ 54.4 m².
54.4 m² ÷ 2.88 m² per board ≈ 19 boards. Add 10% waste for cuts around windows, sockets and pipes, and you're ordering 21 boards.
Don't forget the fixings
- Drywall screws: roughly one screw every 300 mm along each stud — budget a box of 1000 for a room this size.
- Adhesive (for dot-and-dab): manufacturers quote coverage per bag — check the bag, not the folklore.
- Skimming plaster: coverage varies a lot by brand and thickness; the tub will state m² per bag at a given thickness.
Tape, corner bead and jointing compound round out the list. Everything is cheaper in bulk from a builders' merchant than from a DIY shed — worth phoning two or three merchants with the same list.