Wastage accounts for cuts, breakages, and future replacements. 10% is standard; allow 15–20% for diagonal patterns or complex cuts.
This calculator divides your total area by the area of a single tile, then adds your wastage percentage to account for cuts and breakages. Wastage of 10% is a reasonable baseline for a straightforward grid layout. Diagonal or herringbone patterns waste more material — use 15–20% in those cases. If you know how many tiles come in a box, enter that to get an exact box count.