How many plasterboard sheets for a wall or a ceiling

The formula, and one wall end to end

to cover = area × layers × (1 + waste) · sheets = to cover ÷ sheet area, rounded up · studs = run ÷ spacing, rounded up, + 1

Take a wall 5 m long and 2.6 m high — 13 m² of visible face — boarded in one layer with 10% waste. That means covering 14.3 m².

A 120 × 250 cm board is 3 m², so 14.3 ÷ 3 = 4.77 — and boards are not sold in fractions, so it rounds up to 5 sheets. That buys 15 m², i.e. 0.7 m² more than the calculation asks for.

The 10% waste is an editable planning starting point, not a norm and not a prescribed quantity. It covers cuts around openings, corners and damaged edges, not a measuring mistake.

What is interesting is how blunt that setting is on a small wall: 0%, 5%, 10% and 15% all give the same 5 sheets. Only at 20% does it cross the line and buy a sixth.

A bigger board does not mean less material

All four common sizes give a different piece count but not a different quantity. A 120 × 200 cm board takes 6 pieces and a 120 × 300 cm board only 4 — and both end up at exactly 14.4 m².

The difference is elsewhere: fewer boards means fewer joints to tape and fill, but heavier pieces to carry and lift. Working alone, four 3.6 m² boards are not necessarily an easier job than six 2.4 m² ones.

So compare products by square metres and by the number of joints, not by how many pieces end up in the calculation.

Layers are not the same as sides

This is the most common input mistake. A partition is boarded on both sides, and that is double the area — not double the layers. For our wall that means 26 m², not 13 m² in two layers.

The sheet count comes out the same: 26 m² in one layer and 13 m² in two layers both need 28.6 m² and 10 sheets. But those are not the same walls, and everything else about them differs.

The joint compound shows the difference. It is calculated on the net visible face, without multiplying by layers and without waste, because you finish one visible surface however many boards sit behind it. For 13 m² in two layers, that is still 13 m² to finish.

There is one more stud than there are spacings

A 5 m run at 60 cm centres has 9 spacings but 10 studs — because both the start and the end of the wall carry one. That “plus one” is the mistake people most often miss, and it always goes the expensive way, because it under-orders.

The spacing is your choice and the rest is pure arithmetic: a closer spacing means more studs and more running metres of profile. On the same wall, 40 cm centres need 14 studs and 36.4 m of profile, while 62.5 cm centres need only 9 studs and 23.4 m.

Which spacing is right for your wall is in the system's own data sheet and depends on the height, the board thickness and the number of layers — the tool prescribes nothing, it just counts from the spacing you give it.

Studs are not spliced; track is

A stud runs floor to ceiling in one piece. That is why a 4 m profile yields only ONE 2.6 m stud plus 1.4 m of offcut — not 1.54 studs. 10 studs need 10 pieces.

The track at the floor and the ceiling is butted end to end, so that is a plain division: 2 × 5 m = 10 m, which from 4 m stock is 3 pieces.

So the stock length decides the order more than it looks. A 4 m profile gives 10 + 3 = 13 pieces, while a 5.2 m profile gives 5 + 2 = 7 for the same wall — because 5.2 m yields two 2.6 m studs with nothing left over.

And the round-down has to be exact. A 6.6 m profile against a 2.2 m wall yields exactly three studs; a calculation that rounds that error down reports two and orders 5 pieces where 4 are needed.

If the profile is shorter than the wall is high, the tool says so as its own case and offers no piece count — the boards and the stud count are still correct answers, only the piece count is impossible.

The ceiling is counted; its grid is not

For a suspended ceiling you enter the length and the width of the room. A 4 × 5 m room is 20 m², 22 m² with 10% waste, so 8 boards of 3 m².

The ceiling grid is deliberately not estimated. Hangers, primary and secondary channels and the perimeter trim have their own layout, which depends on the system and on the drop, we have not researched it, and borrowing the wall model would be worse than an honest gap. That is why every framing field appears in wall mode only.

For the same reason the tool does not estimate joint tape: its length depends on the board layout — which way they run and how many butt joints there are — not on the area.

Screws and compound: the numbers come from your system

Screws and joint compound have no prefilled value, and that is deliberate: screw density depends on the board thickness, the spacing and the number of layers, and compound consumption on the level of finish. Both figures exist — in the system's data sheet and on the bag.

The tables below only show how sensitive those items are. Screws are counted on the area with waste, so on 14.3 m² the difference between 12 and 30 per square metre is the difference between 172 and 429 pieces.

The compound goes on the net visible face. On 13 m² all three rates shown fit into a single 20 kg bag; on 40 m² they diverge — 32 kg is two bags, while 48 and 60 kg are three.

Check your own numbers

Open the calculator with this article's wall, swap the measurements for your own and add the figures from your system wherever you have them. Groups you leave empty are simply not shown, while the rest of the calculation still stands.

For the compound and the bags, the table below shows the same calculation on the small wall and on a larger ceiling — the rounding up is the whole story there, because you cannot buy half a bag.

Open the calculator with this article's wall →