Plasterboard calculator: how many boards do I need, and what will they cost?
Choose walls or ceiling, put in your sizes and pick a board. You'll see how many boards to order and roughly how many bags of multi-finish you'll need to skim them.
Area to board
31.6 m²
Boards to order
13
Multi-finish (25kg)
4 bags
Board size
2400 × 1200mm
Finish plaster is based on about 10m² per 25kg bag at 2mm. Check the bag, because coverage varies by brand and wall.
How it works
1For walls, add up the length of every wall you're boarding and measure the height. For a ceiling, measure the room length and width.
2Take off doors and windows. A standard internal door is about 1.6m² and an average window is about 1–1.5m².
3Pick your board. A 2400 × 1200mm (8×4) board covers 2.88m², while a 1800 × 900mm (6×3) board covers 1.62m². 6×3s are easier to handle on your own, especially on ceilings.
4Add a cuts allowance. 10% is usual for a room with a few openings. Go for 15% if there are lots of reveals or awkward angles.
5Check the finish plaster. Multi-finish at about 2mm covers roughly 10m² per 25kg bag.
6×3 or 8×4 plasterboard?
8×4 (2400 × 1200mm) — covers 2.88m² a board, so fewer joints to finish. The trade choice, but heavy and awkward above head height.
6×3 (1800 × 900mm) — covers 1.62m² a board. Easier to get upstairs and to handle solo, especially on ceilings, at the cost of more joints to tape.
Multi-finish plaster coverage
A 25kg bag of multi-finish plaster covers roughly 10m² of board at a 2mm skim — call it a room's worth of wall per bag and a bit left over for the reveal. Rough trade guide only; plasterers vary the thickness and the board suction changes how it goes on.
Take your quantities across to Price Planter and compare them across UK builders' merchants — including whether splitting the order across two merchants works out cheaper.