Tile Calculator (Tiles & Boxes with Waste)
Enter the floor or wall size (or total square feet), the tile size and the waste %. Get the tile count and boxes to buy. Free, no sign-up.
How many tiles do I need?
A tile estimate has three parts: the area to cover, the area of one tile, and an allowance for the tiles you'll cut, break or set aside as spares.
1. Measure the area
For a rectangular floor or wall, multiply length × width in feet. For an L-shaped bathroom, split it into two rectangles and add them, or use the area calculator and type the total into the "total sq ft" box. Leave out spots that won't be tiled, such as under a fitted vanity or a tub, if you're sure of them.
2. Area of one tile
Tile sizes are given in inches, so multiply width × length and divide by 144 to get square feet. A 12 × 24 in tile is 288 ÷ 144 = 2 sq ft, a 12 × 12 is 1 sq ft, and a 3 × 6 in subway tile is 0.125 sq ft (8 tiles per square foot). Grout joints make each tile cover a little more. Enter the joint width to include it, or leave it at 0 for a slightly cautious count.
3. Add waste
Every row that meets a wall needs a cut, and offcuts often can't be reused. A common rule of thumb is to add about 10% for a straight lay and about 15% for diagonal or herringbone patterns, with more for small, awkward rooms. Your installer or the tile maker may recommend a different figure, so follow them if they do.
Worked example: an 8 × 10 ft bathroom floor is 80 sq ft. With 10% waste that's 88 sq ft. 12 × 24 tiles cover 2 sq ft each, so 88 ÷ 2 = 44 tiles. Sold 8 to a box, that's 44 ÷ 8 = 5.5, so buy 6 boxes (48 tiles). Laid diagonally at 15%, it's 92 sq ft = 46 tiles, still 6 boxes.
Why buy a few spares
Colour and shade can vary between production runs (often marked as a lot or batch number on the box). Buying all your tile at once from the same lot, and keeping a few spare tiles after the job, makes a future repair much easier to match.
Tiles per square foot
| Tile size | Sq ft per tile | Tiles per sq ft |
|---|---|---|
| 3 × 6 in | 0.125 | 8 |
| 4 × 4 in | 0.111 | 9 |
| 6 × 6 in | 0.25 | 4 |
| 12 × 12 in | 1 | 1 |
| 12 × 24 in | 2 | 0.5 |
| 18 × 18 in | 2.25 | 0.444 |
| 24 × 24 in | 4 | 0.25 |
Walls and backsplashes
For a wall, measure the width and the height you're tiling and multiply, then subtract windows and large openings. A kitchen backsplash 12 ft long and 18 in high is 12 × 1.5 = 18 sq ft. In 3 × 6 in subway tile (8 per sq ft) with 10% waste that's 19.8 sq ft × 8 = 158.4, so 159 tiles. Outlets and switch boxes still need cut tiles around them, so don't subtract them. Trim pieces such as bullnose or edge profiles are sold by the linear foot or piece, so measure the edges you need to finish separately.
Common mistakes
| Mistake | Fix |
|---|---|
| Dividing square feet by tile inches | Convert the tile to sq ft first (in × in ÷ 144) |
| No waste allowance | Add about 10% for straight lay, about 15% for diagonal |
| Rounding boxes down | Always round boxes up; partial boxes aren't sold |
| Mixing lots | Check the lot number on every box before you start |
Related: flooring square footage with waste, area calculator, feet-inch to decimal chart.
FAQ
How many tiles do I need for 100 square feet?
Add waste first: 100 sq ft + 10% is 110 sq ft. With 12 × 12 in tiles (1 sq ft each) that's 110 tiles. With 12 × 24 in tiles (2 sq ft each) it's 55.
How much extra tile should I buy?
A common allowance is about 10% for a straight lay and about 15% for diagonal or herringbone patterns, with more for small rooms with many cuts.
How do I convert tile size to square feet?
Multiply the tile's width by its length in inches and divide by 144. A 12 × 24 in tile is 2 sq ft.
Should I count grout lines?
Grout joints make each tile cover slightly more area, so leaving them out gives a slightly higher, more cautious count. Enter the joint width to include them.