How Many Tiles Do I Need?
Calculate the net surface area, divide by one tile's face area, then add the waste allowance used for your layout.
Formula
Tile area = tile length × tile widthTiles = surface area ÷ tile area × (1 + waste rate)A 20 m² floor with 500 × 500 mm tiles needs 80 tiles before waste. With 10% extra, the result is 88 tiles.
Floor and wall projects
For walls, subtract doors and windows that will not be tiled before calculating tile quantity. Use actual tile dimensions and keep the extra allowance visible.