Paint & Flooring
Tile Calculator
Calculate how many tiles and boxes you need for a floor tile job, shower wall or backsplash. Enter the area, tile size and grout joint, and this tile calculator gives tiles per square foot, the total with layout waste, boxes to buy and the cost.
Result
Enter your measurements and press Calculate. What to buy, the working and the cost will appear here.
How to use the tile calculator
- Add the areas to tile (floor, shower walls, backsplash), and subtract anything not tiled such as a vanity footprint.
- Choose the tile size or enter a custom size, and the grout joint width.
- Set the layout waste: 10% straight, 15% diagonal or herringbone.
- Enter tiles per box to count boxes, add a price, and press Calculate.
How many tiles do I need?
tiles per ft² = 144 ÷ ((tile length + joint) × (tile width + joint))
tiles = area × tiles per ft² × (1 + waste)
For 12 × 24 in tile with 1/8 in joints: 144 ÷ (24.125 × 12.125) = 0.49 tiles per ft². A 60 ft² bathroom floor takes 30 tiles, or 33 with 10% waste.
Worked example: a bathroom floor
A 10 × 8 ft bathroom floor, minus a 5 × 2.5 ft tub, is tiled with 12 × 24 in porcelain, 8 tiles to a box at $42 per box:
- Area 1: 10 ft × 8 ft = 80 ft²
- Area 2 (subtracted): 5 ft × 2.5 ft = 12.5 ft²
- Tiles per ft²: 1 ft² ÷ (24.125 in × 12.125 in) = 0.492
- Tiles: 67.5 ft² × 0.492 = 33.2 × 1.1 → 37
Tiles to buy: 37; Boxes: 5 boxes; Tile area to buy: 80 ft²; Estimated cost: $210.00. Open this example in the calculator.
Tiles per square foot
| Tile | Per ft² (1/8 in joint) | Per 100 ft² |
|---|---|---|
| 12 × 12 in | 0.98 | 98 |
| 12 × 24 in | 0.49 | 50 |
| 18 × 18 in | 0.44 | 44 |
| 24 × 24 in | 0.25 | 25 |
| 6 × 24 in (wood-look plank) | 0.97 | 98 |
| 4 × 4 in | 8.46 | 847 |
| 3 × 6 in (subway) | 7.52 | 753 |
How much extra tile should I buy?
- 10% for straight layouts in simple rooms.
- 15% for diagonal, herringbone or offset patterns, and for large-format tile where each cut wastes more.
- 20% or more for small rooms with many cuts, niches and corners.
- Keep spares: future repairs need tile from the same lot.
Grout, thinset and trim
Tile also needs thinset mortar (follow the bag’s coverage for your trowel size), grout, and trim pieces such as bullnose or edge profiles. The grout calculator works out bags from your tile size and joint width.
Assumptions and limitations
- Tile sizes are nominal; enter the actual size for rectified or metric tile.
- Areas are flat; for shower walls, enter each wall’s width and height as rectangles.
- Mosaic sheets are counted by sheet: enter the sheet size as a custom tile with a zero joint.
Tile questions
How many 12 × 12 tiles do I need for 100 square feet?
About 98 tiles with 1/8 in joints, or 108 with 10% waste.
How many 12 × 24 tiles are in a square foot?
About 0.49, so roughly one tile per 2 ft² once joints are included.
How do I calculate tile for a shower?
Measure each wall’s width and height to where the tile stops, add them as rectangles, subtract any niche or window, and add 15% for the extra cuts.
Formulas, unit conversions and default values are explained on our methodology page. Results are estimates; check manufacturer data and local codes before you buy or build.