Tile calculator
Tiles and boxes from room size and tile dimensions, with a waste allowance you control. Works for floors and walls.
- Area to cover
- — ft²
- Tiles needed
- —
- Coverage bought
- — ft²
How the calculation works
area = length × width
Add the waste percentage, divide by the area of one tile (width × height ÷ 144), and round up. Boxes come from the coverage printed on the box — the number that actually matters at checkout.
tiles = area × (1 + waste) ÷ tile area in ft²
Why the waste allowance is not optional
Tiles break, cuts fail, and you cannot buy the same dye lot six months later. Ten percent covers a normal rectangular room. Diagonal layouts waste more because every edge tile is cut twice; herringbone wastes the most because the pattern forces half-tile starts.
Worked example
A 12 × 10 ft room is 120 ft². With 10% waste that is 132 ft². With 12 × 12 in tiles (1 ft² each) you need 132 tiles. At 15 ft² per box: 132 ÷ 15 = 8.8, so buy 9 boxes — 135 ft².
Waste by layout
| Layout | Waste | Why |
|---|---|---|
| Straight, open room | 5–7% | Few cuts |
| Straight, many doorways | 10% | Cut tiles at each opening |
| Diagonal (45°) | 15% | Two cuts per edge tile |
| Herringbone | 20% | Half-tile starts at every row |
Frequently asked
Does grout change the tile count?
Only marginally. A 1/8" grout joint adds roughly 1–2% to coverage, which the waste allowance already covers. Do not reduce waste for grout.
Should I buy all boxes at once?
Yes. Dye lots vary between production runs, and a patch of slightly different tile in the middle of a floor is visible under daylight.
How do I handle a wall with a window?
Measure the full wall and subtract the window opening, then keep the 10% waste. The cut pieces around a window are usually unusable elsewhere.