How Much Plasterboard Do I Need? (UK Guide)

Before you count anything, know what one sheet covers. In the UK the standard tapered-edge plasterboard sheet is 2400mm x 1200mm, which is 2.88 square metres. That's the size you'll be handed at Travis Perkins, Jewson or Wickes unless you ask for something else.

There's also a smaller 1800mm x 900mm board (1.62 m²) that a lot of DIYers prefer, because a full 8ft sheet is heavy and awkward to lift solo. It costs a little more per square metre and means more joints to fill, but if you're working alone it can be worth it. The maths below works for either. Just divide by the area of the sheet you're actually buying.

Takeaway: the default UK sheet is 2.4m x 1.2m = 2.88 m². Know your sheet size before you count, or every figure after it is wrong.

Boarding is an area calculation, and it's simpler than people expect.

Sheets = total area to board ÷ area of one sheet, then add waste, then round up.

Work out the area you're covering in square metres, divide by 2.88 for a standard sheet, add around 10% for cuts and offcuts, and round up to the next whole sheet. You can't buy two-thirds of a board.

The only part that trips people up is the "total area to board", and that changes depending on whether you're doing a wall, a whole room, or a ceiling.

A single wall: length times height gives you one face. If you're boarding both sides, which you almost always are on a stud wall, double it. A 3.6m long wall at 2.4m high is 8.64 m² a face, so 17.28 m² for both sides. Divide by 2.88, add 10%, and you're at 7 sheets.

A whole room (walls): add up the length of every wall to get the perimeter, multiply by the ceiling height, then take off the door and window openings. A 4m x 3m room has a 14m perimeter. At 2.4m high that's 33.6 m². Knock off roughly 1.8 m² for a door and you're at about 31.8 m². Divide by 2.88, add 10%, round up: 13 sheets.

A ceiling: ceilings are just length times width. A 4m x 3m ceiling is 12 m². Divide by 2.88, add 10%, round up: 5 sheets. Ceilings feel harder because you're boarding above your head, but the sum is the easy bit.

Takeaway: area divided by 2.88, plus 10%, rounded up. The only thing that changes between a wall, a room and a ceiling is how you work out the area.

The waste figure isn't a guess plucked out of the air. On a simple square room with full sheets and few openings, you'll waste very little, and 5% covers it. On a room full of windows, sloping ceilings, or a stairwell where every board needs cutting to a shape, you can lose 15% or more to offcuts you can't reuse.

For most jobs, 10% is the honest middle. It leaves you a spare board or two rather than a van-load, and it covers the sheet that gets cracked carrying it up the stairs, which does happen. If your room is all awkward angles, bump it to 15%.

Takeaway: 10% waste suits most rooms. Drop to 5% for a plain box, push to 15% for anything full of cuts and angles.

Not all plasterboard is the same, and buying the wrong type is a more expensive mistake than buying the wrong number.

Plasterboard is made to BS EN 520, and the requirements for where each grade is needed come from the Building Regulations, in particular Approved Document B for fire and Approved Document E for sound. If a wall separates a garage from living space, or a flat from a neighbour, the board type isn't optional.

Takeaway: match the board to the room. Green for wet rooms, pink for fire, acoustic for quiet. Getting the count right on the wrong board helps no one.

Put it together on a real job. You're boarding out a spare bedroom in a Nottingham semi, 4m x 3m, with a 2.4m ceiling. You're doing the four walls and the ceiling, with one door in the room.

On price, a standard 12.5mm 2.4m x 1.2m board runs roughly £10 to £13 in 2026 at a merchant like Jewson. So 17 sheets is somewhere around £170 to £220 in board, before you add screws, jointing tape and filler. A typical box of 1000 drywall screws is about £8 to £12 and will comfortably cover a room this size, since you're fixing at roughly 200mm to 300mm centres.

Takeaway: a standard spare room is around 17 sheets and £170 to £220 in board in 2026. Add screws and jointing and you're still under £250 for materials.

Here's the contrarian point. Plenty of guides tell you to work out your square metres and stop there. What they don't mention is that merchants often sell and price plasterboard in packs, and a pack might be 40, 50 or 72 sheets. If your job needs 17 sheets, you don't want to accidentally order a pallet.

Always order loose sheets for a domestic job unless you genuinely need dozens, and check the price is per sheet, not per pack, before you pay. It sounds obvious, but the number of people who've come home with three times the board they needed because the website priced by the pack is not small. Work out your sheet count first, then buy exactly that many.

Takeaway: know your sheet count before you look at prices, and check whether you're buying by the sheet or by the pack. The maths protects you from the upsell.

Rather than run the areas by hand, put your measurements into the Plasterboard Calculator. Enter your walls and ceiling and it works out the total area, the waste allowance and the exact number of sheets, ready to take to the merchant. If you're building the partition those boards are going onto, the Stud Wall Calculator UK does the timber to match.