Tile, laminate and paint calculator
How many boxes and litres to buy
- Area
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Walls are worked out as the room's perimeter times its height, with nothing added for alcoves or pillars. Measure the room and check the details on the packaging before you buy.
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Enter the room's length and width, a cutting allowance and the m² per box to see how many boxes of tiles or packs of laminate to buy. A 4 × 3.5 m room is 14 m², or 15.4 m² with 10% extra, which means 11 boxes of 1.44 m². For painting it works out litres for walls and ceiling.
How it works
Floor area is length times width. Wall area is the perimeter, 2 × (length + width), times the height, minus doors and windows. The allowance goes on top, the total is divided by the m² in a box and rounded up, because shops don't sell half a box.
How much extra you need depends on the pattern. Tiles laid straight need about 10%, while diagonal or herringbone patterns need 15%. Laminate usually needs 5 to 8%. A small room with lots of corners wastes more than a large rectangular one.
For paint: litres = area × coats / coverage. Coverage is printed on the tin, usually 6 to 10 m² per litre. On fresh plaster or with strong colours, allow for a third coat.
Worked example
Bathroom: floor 2.2 × 1.8 m, walls tiled up to 2 m, door 0.7 × 2 m. In “Wall tiles” the walls come to 2 × (2.2 + 1.8) × 2 − 1.4 = 14.6 m². With 10% extra that's 16.06 m², so with 1.5 m² boxes you need 11 boxes. The 3.96 m² floor with 15% extra takes 4 boxes.
Laminate in a 4 × 3.5 m bedroom: 14 m², 7% extra, packs of 2.13 m². You need 15 m², which is 8 packs.
Painting the same room, ceiling included, walls 2.6 m high, door and window 3.6 m²: 35.4 m² of wall plus 14 m² of ceiling. Two coats at 8 m² per litre need 12.4 litres.
Questions people ask
How many tiles do I need for 10 m²?
With 10% extra you need 11 m². In boxes of 1.44 m² that's 8 boxes (11.52 m²); in 1 m² boxes, 11.
Why buy all the tiles at once?
Tiles from different batches vary in shade and sometimes in size by a millimetre or two. The batch number is printed on the box, so check it's the same on every one. A spare box is worth keeping in case a tile cracks later.
Paint is sold by the kilo, not the litre. What now?
Enter the coverage in m² per kilogram and the weight of the tub instead of litres, then read the result in kilograms. In Serbian DIY shops wall paint (poludisperzija) is often sold this way.
Do I take off doors and windows?
For wall tiles and painting, yes: enter their area in “Doors and windows”. On a floor there's nothing to subtract, and the threshold and edges round the door frame eat into the allowance anyway.
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Updated: 13 November 2026