Tile Calculator: How Many Tiles and Boxes for a Floor or Wall?
Estimate tiles for a floor, backsplash or shower wall from the area, tile size, grout joint and a waste allowance, and convert the result into boxes.
How the calculation works
The calculator divides the area you are tiling by the area one tile covers, including its share of the grout joint, then adds a waste allowance.
- Area = length × width in feet. For an L-shaped room, split it into rectangles and add them.
- Tile footprint = (tile length + joint) × (tile width + joint), in inches, divided by 144 to get square feet.
- Tiles = area ÷ tile footprint.
- Add waste for cuts, breakage and future repairs. The field starts at 10 percent as an example. Diagonal layouts, herringbone patterns and rooms with many corners need more.
- Boxes = tiles ÷ tiles per box, rounded up, if you enter the box count from the packaging.
Worked example
An 8 × 5 ft bathroom floor with 12 × 12 inch tiles and a 1/8 inch grout joint, with 10 percent waste:
| Step | Value |
|---|---|
| Area | 8 × 5 = 40 sq ft |
| Tile footprint | (12.125 × 12.125) ÷ 144 ≈ 1.02 sq ft |
| Tiles before waste | 40 ÷ 1.02 ≈ 39.2 |
| Plus 10% | 43.1, so 44 tiles |
If the tiles come 10 to a box, buy 5 boxes. Keep the leftovers: a few spare tiles from the same production lot make a future repair match.
Why the grout joint matters
For large tiles, the joint barely changes the count. For small tiles and mosaics, it adds up. Including it gives a slightly lower and more accurate count, but the waste allowance usually matters more than the joint.
Buying tips
- Check the lot or shade number on every box. Tiles from different production runs can vary in color.
- Buy extra for patterns. Herringbone, diagonal and large-format tiles produce more offcuts.
- Do not forget trim pieces, such as bullnose or edge trim, which are usually counted by length.
- Plan setting materials: thinset or adhesive, grout, spacers, and for showers, a waterproofing system.
Wet areas and old floors
In showers and tub surrounds, the tile is only the visible surface; the waterproofing behind it keeps water out of the wall. The EPA’s mold guidance stresses that the key to mold control is moisture control, so take the backer and waterproofing as seriously as the tile itself. When removing old flooring, note that the EPA lists vinyl floor tiles and the backing on vinyl sheet flooring and adhesives among products that may contain asbestos; have old flooring tested before tearing it out.
Limits of this estimate
The calculator assumes a simple rectangle with full-size tiles. Layout choices, such as centering tiles in a room or around a fixture, can change the number of cut pieces. If the room is irregular, sketch it on graph paper and count tiles by row for a closer estimate.