Tile is sold by the box, laid with gaps, and cut at every edge — which makes “how many tiles do I need?” harder than it first looks. This calculator takes your area, tile size, grout joint width, and a waste allowance, then tells you how many tiles to buy and how many boxes that works out to.
It works for floor and wall tile: ceramic and porcelain squares, large-format tiles, and rectangular planks. Enter the tile dimensions printed on the box, and check the tiles-per-box figure there too, because it varies by product.
Tile Calculator
Worked example: a bathroom floor
Say you are tiling a bathroom floor that measures 8 × 5 ft, using 12 × 12 in tiles with a 1/8 in grout joint, a standard 10% waste allowance, and boxes of 10 tiles.
- Area: 8 × 5 = 40 sq ft
- Each tile plus its share of the grout joint covers 12.125 × 12.125 in = 147.0 sq in ≈ 1.02 sq ft
- Tiles before waste: 40 ÷ 1.02 = 39.2 tiles
- With 10% waste: 39.2 × 1.10 = 43.1, rounded up to 44 tiles
- Boxes: 44 ÷ 10 = 4.4, rounded up to 5 boxes
Those five boxes also leave you a few spare tiles from the same dye lot, which is exactly what you want if a tile ever cracks years from now.
How the calculation works
Tiles needed = ceiling( area ÷ tile coverage × (1 + waste %) ), where tile coverage uses the tile size plus the grout joint: coverage = (tile length + joint) × (tile width + joint) ÷ 144.
Counting with the grout joint included is the standard estimator’s convention: each tile “occupies” its own face plus half a joint on every side. It slightly reduces the count compared with ignoring grout, and it matches how the layout actually covers the floor. The default waste allowance is 10%, the trade standard for straight layouts; diagonal and herringbone patterns cut more tiles, so use 15% for those. Boxes are always rounded up to a whole box.
Typical tile costs
Typical US prices, checked November 2026. Materials only; setting materials (thinset, grout, backer board) are extra and vary by region and store.
| Tile type | Typical cost per sq ft |
|---|---|
| Ceramic floor tile | $1.50 – $5.00 |
| Porcelain tile | $3.00 – $10.00 |
| Natural stone tile | $5.00 – $15.00 |
| Mosaic tile (mesh sheets) | $5.00 – $15.00 |
For the worked example above, five boxes of a mid-range ceramic at roughly $1.50 – $3.00 per sq ft of coverage puts the tile itself at about $75 – $150.
Before you order
- Measure the area carefully — if you have not yet, run the room through the Square Footage Calculator method: rectangles added together.
- Subtract only areas that will not be tiled, such as a built-in tub footprint on a bathroom floor. Tile usually runs under vanities and toilets.
- Copy the tile size, grout joint, and tiles-per-box figures from the actual product box, not a listing photo.
- Use 10% waste for straight grids and 15% for diagonal, herringbone, or large-format layouts with many cuts.
- Order everything in one purchase so all boxes come from the same dye lot, and keep one box unopened as spares if the budget allows.
FAQ
How many tiles do I need for 40 square feet?
With 12 × 12 in tiles, a 1/8 in grout joint, and 10% waste: 44 tiles, which is 5 boxes of 10. Smaller tiles need more pieces — and more grout lines — for the same area.
Does grout joint width really change the tile count?
Slightly. A wider joint means each tile covers a little more floor, so you need marginally fewer tiles. On a 40 sq ft bathroom the difference between a 1/16 in and a 3/16 in joint is only a tile or two, but on a large floor it adds up, which is why the calculator includes it.
How much extra tile should I buy for cuts and breakage?
Ten percent is the standard allowance for a straight layout in a rectangular room. Go to 15% for diagonal patterns, rooms with many corners, or large-format tiles, where one miscut wastes a big piece.
How many square feet are in a box of tile?
It depends on the product — commonly 10 to 15 sq ft for floor tile. The coverage is printed on the box. This calculator works in tiles per box, so divide the box coverage by the area of one tile if the label only shows square feet.
Can I use this calculator for a shower or backsplash wall?
Yes — the math is identical for walls. Measure the wall area (height × width, minus openings you will not tile), and for mosaic sheets, treat one sheet as one “tile” with the sheet dimensions.
Related calculators
Start with the Square Footage Calculator if you still need the area itself. Comparing tile against other floors? The Flooring Calculator covers LVP, laminate, and hardwood in the same boxes-and-waste terms. For the walls around a tiled shower, the Drywall Calculator estimates backer and wallboard sheets, and the Paint Calculator handles the painted parts of the room.
Estimates only: results are based on standard formulas and typical material sizes, and actual quantities vary with layout, site conditions, and the product you choose. Confirm your measurements and the specifications on the box before buying. These tools do not cover structural, load-bearing, electrical, gas, or plumbing design — for safety-critical work, hire a licensed professional.