Tile is sold by the piece or by the box, but planned by area. This tile calculator connects the two: measure the floor or wall, enter your tile size, and it works out the area, adds a waste allowance for cuts and breakages, and tells you how many tiles and how many boxes to buy, along with the cost.
How to use the tile calculator
- Measure the surface. For a floor, measure length and width. For a wall or backsplash, measure the width and the height to be tiled.
- Enter the tile size in inches, for example 12 × 24. The calculator works out the area of one tile.
- Choose a waste allowance for your layout (see the table below).
- Optional: enter the coverage per box from the label and the price per square foot to get the number of boxes and the total cost.
- Several areas? Add each one to the total. Subtract windows, doors or a bath that won’t be tiled.
How the tile count is worked out
Tiles = (area × (1 + waste %)) ÷ area of one tile, rounded up
The area of one tile in square feet is its length × width in inches, divided by 144. A 12 × 24 in tile is 288 ÷ 144 = 2 sq ft. The calculator uses the tile’s stated size and ignores the grout joints, which slightly overestimates the count: a safe direction to round.
How much waste to allow for tile
| Layout | Typical waste |
|---|---|
| Straight grid, simple room | 10% |
| Offset or brick pattern | 10–15% |
| Diagonal (45°) | 15% |
| Herringbone or chevron | 15–20% |
| Large-format tiles (24 in and up) | Add 5% more – offcuts are bigger |
| Small rooms with many cuts | Add 5% more |
Keep a few spare tiles after the job. Tile ranges are discontinued and colours vary between batches, so a matching replacement can be impossible to find later.
Tiles per 100 square feet
A quick reference for common sizes. Multiply by your area in hundreds of square feet for a rough count.
| Tile size | Area per tile | Tiles per 100 sq ft | With 10% waste |
|---|---|---|---|
| 4 × 4 in | 0.111 sq ft | 900 | 990 |
| 6 × 6 in | 0.25 sq ft | 400 | 440 |
| 3 × 6 in | 0.125 sq ft | 800 | 880 |
| 4 × 12 in | 0.333 sq ft | 300 | 330 |
| 12 × 12 in | 1 sq ft | 100 | 110 |
| 6 × 24 in | 1 sq ft | 100 | 110 |
| 12 × 24 in | 2 sq ft | 50 | 55 |
| 18 × 18 in | 2.25 sq ft | 45 | 49 |
| 24 × 24 in | 4 sq ft | 25 | 28 |
| 8 × 48 in | 2.667 sq ft | 38 | 42 |
| 24 × 48 in | 8 sq ft | 13 | 14 |
Worked example: bathroom floor
- Floor: 8 × 5 ft = 40 sq ft.
- Add 10% waste: 40 × 1.10 = 44 sq ft.
- 12 × 24 in tiles are 2 sq ft each: 44 ÷ 2 = 22 tiles.
- Boxes cover 16 sq ft (8 tiles): 44 ÷ 16 = 2.75, so 3 boxes (48 sq ft, 24 tiles).
- At $3.99 per sq ft: 48 × 3.99 = $191.52.
Walls, showers and backsplashes
Treat each wall as a rectangle: width × height to the top of the tiling. Add the walls together and subtract windows and doors. Leave small items such as outlets in the area; the cuts around them use tile anyway. For a backsplash, measure the run of countertop and the height up to the cabinets, and remember the short returns at the ends.
Before you buy
- Check the batch or shade number on every box so the colour matches.
- Buy trim pieces, bullnose or edge profiles separately; they are sold by the piece or by the linear foot.
- Allow for thinset mortar and grout; each bag’s coverage is printed on the label and depends on the trowel and joint size.
- Confirm that the floor is flat and stiff enough for your tile size, especially for large-format porcelain.
Frequently asked questions
How many tiles do I need for 100 square feet?
It depends on the tile size: 100 tiles of 12 × 12 in, 50 tiles of 12 × 24 in, or 25 tiles of 24 × 24 in, before waste. Add 10–15% for cuts.
How do I calculate the area of one tile?
Multiply the tile’s length by its width in inches and divide by 144 to get square feet. A 6 × 24 in tile is 144 ÷ 144 = 1 sq ft.
How much extra tile should I buy?
Allow about 10% for straight layouts and 15–20% for diagonal, herringbone or large-format tiles.
Do grout lines change the number of tiles?
Slightly. Grout joints mean each tile covers a little more than its own size, so ignoring them, as this calculator does, gives a small safety margin.
How many tiles are in a box?
It varies by product. The box label lists the number of pieces and the square feet covered; enter the coverage in the calculator to get the number of boxes.
How do I calculate tiles for a wall?
Multiply the wall’s width by the height to be tiled, subtract windows and doors, then divide by the area of one tile and add waste.
Should I round up to whole boxes?
Yes. Tile is sold in whole boxes, and having a few spares for repairs is good practice.