Follow each quantity separately
For a 7.68 m² floor, a selected 10% allowance adds 0.768 m². The target becomes 8.448 m². Boxes covering 1.8 m² round the order to 5 boxes, or 9 m².
In that example, box rounding adds 9 − 8.448 = 0.552 m² beyond the target. The total purchased area exceeds the measured floor by 1.32 m², but cuts and breakages can consume that material.
Choose an allowance for the actual layout
The correct allowance depends on details the simple area model does not know, such as tile dimensions, the pattern, cuts and the shape of the space. Use the supplier or installer’s advice for the product and layout you choose. The calculator’s 10% starting value is an editable example.
The tile quantity calculator keeps your allowance separate from purchased coverage. It does not produce a verified cutting plan or predict usable spare tiles.
Compare whole-box costs
Compare alternatives using the final number of boxes and price per box. A product with a smaller pack may leave less purchased coverage above the target, but the overall cost still depends on its pack price.
See the full tile box calculation example before printing your list.