From square metres to whole boxes
Tile area = width (cm) × length (cm) ÷ 10,000
Required area = net area × (1 + waste/100)
Pieces = round up (required area ÷ tile area)
Boxes = round up (pieces ÷ tiles per box)
Rounding happens first to whole tiles and then to whole boxes. The purchased area uses all tiles in those boxes. Do not round the tile area early, especially for small or rectangular formats.
20 m² with 60 × 60 cm tiles
Each tile covers 0.36 m². A 10% allowance gives 22 m². Dividing by 0.36 gives 61.11, so the estimate requires 62 tiles. With four tiles per box, buy 16 boxes: 64 tiles covering 23.04 m².
Choose waste for the actual layout
The default 10% is editable. Room shape, diagonal layouts, tile direction and how offcuts can be reused change the requirement. The percentage alone cannot prove that every cut is possible. Check the intended layout before placing an order and consider keeping suitable spare pieces from the same batch.
Read the box contents carefully
This calculator asks for the number of pieces per box, not square metres per box. Check both dimensions and box contents on the selected product. Irregular shapes, mosaics on sheets and mixed-size patterns need a different area model.
Keep accessories separate
Adhesive and grout do not automatically use the purchased tile area. Their consumption depends on their own product and application details. In the English multi-room project the accessory estimates are simplified; for grout geometry the detailed Italian tool is linked from the catalogue.