Tile Calculator: How Many Tiles and Boxes to Order
Divide the area you are tiling by the area of one tile to get the tile count, then add waste for cuts and breakages. Because tiles are sold by the box, the final step is rounding up to whole boxes — and ordering a spare box is almost always the right call.
Waste allowance by layout
- Straight or grid lay in a simple rectangular room: 10%.
- Brick or offset bond: 10-12%.
- Diagonal lay: 15%.
- Herringbone or chevron: 15-20%, more in small or irregular rooms.
Do not forget adhesive and grout
Adhesive coverage depends on trowel notch size and tile format — large-format tiles need a deeper notch and more adhesive. Grout use rises with wider joints and smaller tiles. Both are sold by weight, and the coverage table on the bag is a better guide than a general rule of thumb.
Order a spare box
Tile batches vary in shade, and discontinued lines are common. One extra box stored flat and dry means a cracked tile in three years is a repair rather than a re-tile. It also protects you if a delivery arrives with breakages, which is routine with ceramic and porcelain.
Key takeaways — Tile Calculator
- Tiles = area ÷ tile area, plus a waste percentage for the chosen layout.
- Round up to whole boxes and add one spare.
- Budget adhesive and grout separately using the bag's coverage figures.