Materials
Cutting a 3200×1600 slab
Where the square metres go, where a joint is unavoidable and why “seamless” happens less often than promised.
July 25, 2026
A 3200×1600 slab is a little over five square metres. A seven-metre kitchen splashback is two slabs, says the calculator. In practice it comes to three, and here is why.
What eats the square metres
The usable yield of a slab is rarely above 75%. The rest goes for four reasons.
- 01 The edge A 20–30 mm technical border runs round the slab: uneven thickness and micro-chips. It is always cut off, even when the piece only just fits.
- 02 Direction of the veining Marble veins run along the slab. You cannot turn a piece sideways to make it fit — the pattern would lie the wrong way.
- 03 Cut-outs Sink, hob, sockets. A cut-out needs a margin against chipping, and the offcuts inside the outline almost always end up as waste.
- 04 Transport breakage One slab in ten arrives with a crack or a chipped corner. That is the industry norm, not a fault of the supplier.
Where the joint will fall
A wall longer than 3.2 metres will have a joint. The only question is where, and that is better settled on paper. A good joint hides in a corner, behind a tap, in the line of the furniture or at a change of plane. A bad one lands in the middle of the wall at eye level, because the cutting was worked out from the offcuts.
A joint is not a defect. The defect is a joint put exactly where the eye lands.
What you get from a slab
| Job | Area | Slabs | Yield |
|---|---|---|---|
| 7 m splashback | 4.2 m² | 3 | 62% |
| Island worktop | 3.4 m² | 2 | 71% |
| Bathroom wall | 6.0 m² | 3 | 78% |
| 24 m² floor | 24 m² | 7 | 74% |
How to work it out before ordering
Send wall elevations with dimensions and the positions of sockets, tap and furniture. We lay the pieces out on the slab to scale and show how many slabs are needed and where the joints will fall. At that stage you can still move the furniture five centimetres and lose one joint.
We work out the cutting free of charge, before the order and with no obligation. The file is yours to keep — you can take it to any contractor.
From the article
The brands in question
The large formats from the article — these four factories.
Slabs up to 3200×1600, 3–20 mm thick
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Large formats and rectified edges
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Concrete and stone, 1200×2600
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Stocked in Spain, dispatch from a week
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Send the elevations
We’ll lay the pieces out on the slab to scale, show the joints and count the exact number of slabs.
Or write to us: info@betton.es · +34 614 805 325