Home & construction
Tile Calculator
Enter the area and your tile size to see the tiles needed, the boxes to buy and the spares left over.
The formula
tile area = width × height ÷ 144
tiles = ⌈ area × (1 + waste ÷ 100) ÷ tile area ⌉
boxes = ⌈ tiles ÷ tiles per box ⌉
Worked example
280 ft² of floor in 12 × 24 in tiles, 10% waste, 8 per box
- 12 × 24 ÷ 144 = 2 ft² per tile
- 280 × 1.10 = 308 ft² to cover
- 308 ÷ 2 = 154 tiles
- 154 ÷ 8 = 19.25 → 20 boxes
Where this goes wrong
Buying the exact number of tiles the area needs
Tiles are sold by the box and cut at every edge, so the arithmetic answer is never the shopping list. A 280 ft² floor needs 154 tiles but 20 boxes — 160 tiles. Ordering 19 boxes leaves you six tiles short with the floor half laid and the range possibly gone.
Questions
- How much waste should I allow for tile?
- Around 10% for a straight lay in a simple rectangular room, and 15% or more for a diagonal or herringbone layout, where every edge tile is a cut. Complicated outlines with alcoves and doorways push it higher still.
- Do I need to allow for grout lines?
- Not in the tile count. A grout joint makes each tile cover marginally more than its own size, so ignoring it errs towards buying slightly too many — which is the safe direction.
- Why keep the spare tiles?
- Because ranges get discontinued and dye lots shift. A single cracked tile three years from now is a repair if you kept spares, and a re-tiled floor if you did not.