The Wall Tile Calculator calculates how many tiles you need for a wall and how many boxes to buy.
It divides the tiled area by the area of one tile including its grout joint — (tile width + joint) × (tile height + joint) — then adds waste and rounds up. Subtract any area that won’t be tiled, such as windows or cabinets, and enter how many tiles come in a box.
Wall Tile Calculator
How many wall tiles and boxes you need — for any tile size and grout joint — with openings and waste.
Formula
Tiles = (W × H − untiled area) ÷ ((tile width + joint) × (tile height + joint)) × (1 + waste %)
Boxes = tiles ÷ tiles per box, rounded up
Where W and H are the width and height of the area to tile.
How the Calculation Works
Step 1: Find the tiled area and subtract anything not tiled.
Step 2: Add the grout joint to the tile’s width and height to get the space each tile really covers.
Step 3: Divide, add waste, and round up to whole tiles and boxes.
Variables Explained
| Input | Meaning | Unit |
|---|---|---|
| Tiled width, height | Size of the area to tile | ft, m |
| Tile width, height | Size of one tile | in, mm |
| Grout joint | Gap between tiles | in, mm |
| Tiles per box | From the box label | tiles |
Example Calculation
Given: backsplash area 10 ft × 4 ft, 12 × 24 in tiles, ⅛ in joint, 10% waste, 8 tiles per box
Area: 40 ft²; tile + joint: 12.125 × 24.125 in ≈ 2.031 ft²
Tiles: 40 ÷ 2.031 × 1.10 ≈ 21.7
Result: 22 tiles = 3 boxes
Common Area Conversion Table
| Unit | Equivalent |
|---|---|
| 1 ft² | 144 in² |
| 1 m² | 10.7639 ft² |
| 12 × 12 in tile | 1 ft² |
| 300 × 600 mm tile | 0.18 m² |
Material Estimation Notes
Tile area is not the same as the amount to buy: boxes cover a fixed area and cut pieces at edges are often unusable. Keep a few spare tiles from the same batch for future repairs, because shades can vary between production runs.
Waste Factor Considerations
The right waste allowance depends on the tile size, the layout (straight, offset, herringbone), the number of outlets, windows and corners, and how brittle the tile is. Large-format and patterned layouts usually need more.
Frequently Asked Questions
How many tiles do I need for a wall?
Divide the tiled area by one tile’s area including the grout joint, then add waste.
How do I calculate tiles for a backsplash?
Measure the length and height of the backsplash, subtract windows, and enter the tile size.
Does the grout joint change the number of tiles?
Yes, slightly — wider joints mean each tile covers more space, so you need fewer tiles.
How many 12 × 24 tiles are in a box?
It varies by product; read the box label and enter it.
Should I subtract windows from tile area?
Yes, subtract areas you won’t tile.