Everyday Tools
Tile Calculator
Enter the room size, tile size, waste allowance, and pricing to see how many square feet you are covering, how many tiles and boxes to buy, and the total cost.
Calculation inputs
Room in feet, tiles in inches. Grout lines are ignored, which slightly overestimates the tile count.
Results
No result yet
Complete the fields and select Calculate to show results here.
About this calculator
This calculator works out how many tiles and boxes you need for a floor or wall, including a waste allowance, and the total cost. It is useful for planning a bathroom, kitchen, or entryway project before you visit the store.
How the calculation works
- Area = room length × width
- Tile area (sq ft) = tile length × tile width ÷ 144
- Tiles = ⌈area ÷ tile area × (1 + waste %)⌉
- Boxes = ⌈tiles ÷ tiles per box⌉
Notes and assumptions
Use about 10% waste for straight layouts and 15–20% for diagonal or herringbone patterns, which create more cut pieces.
Keep a few spare tiles after the job for future repairs.
How it works in plain English
The tool first finds the area to cover by multiplying the room's length by its width in feet. It then finds the area of a single tile by multiplying the tile's length and width in inches and dividing by 144, the number of square inches in a square foot.
Dividing the room area by the tile area gives the bare number of tiles. Real jobs always need extra, because tiles are cut at walls, corners, and fixtures, and some break. The waste percentage is added on top and the result is rounded up to whole tiles. Since tiles are sold in boxes, the tile count is divided by tiles per box and rounded up again.
Cost is either boxes times the price per box or tiles times the price per tile, depending on how the store prices them. Grout lines are ignored, which slightly overestimates the count — a small safety margin. For an L-shaped room, split it into rectangles, run each one, and add the results.
The formula
- Area (sq ft) = room length × room width
- Tile area (sq ft) = tile length (in) × tile width (in) ÷ 144
- Tiles = ⌈area ÷ tile area × (1 + waste %)⌉
- Boxes = ⌈tiles ÷ tiles per box⌉
Worked example
Suppose you are tiling a 12 × 10 ft kitchen with 12 × 12 inch tiles, sold 10 per box at $25 a box, with a 10% waste allowance.
The floor is 120 sq ft and each tile covers 1 sq ft, so you need 120 tiles before waste. Adding 10% gives 132 tiles.
At 10 per box that is 13.2 boxes, rounded up to 14 boxes (140 tiles). The total cost is 14 × $25 = $350. The 8 spare tiles are worth keeping for future repairs, since the same colour lot can be hard to find later.
Suggested waste allowance by layout
| Layout | Typical waste | Why |
|---|---|---|
| Straight / grid | 10% | Cuts only at the room edges |
| Running bond (brick) | 10–15% | Offset rows create more edge cuts |
| Diagonal | 15% | Triangular cuts along every wall |
| Herringbone | 15–20% | Many angled cuts throughout |
| Large format (24 in +) | 15% | Each broken or miscut tile costs more area |
Source: common guidance from tile manufacturers and the Tile Council of North America installation handbook; adjust for your installer's advice.
Frequently asked questions
How much extra tile should I buy?
Around 10% for a simple straight layout in a rectangular room, and 15–20% for diagonal, herringbone, or rooms with lots of corners and fixtures. It is far easier to return an unopened box than to match a colour lot months later.
Do I need to account for grout lines?
Not usually. Grout joints of 1/16 to 1/4 inch slightly reduce the number of tiles you need, so ignoring them, as this tool does, builds in a small extra margin. For very small tiles with wide joints the difference becomes more noticeable.
How do I tile an L-shaped room?
Split the room into two or more rectangles, measure each, and run the calculator for each one. Add the tile counts together, then work out the boxes from the combined total so you are not rounding up twice.
Can I use this for walls?
Yes — enter the wall's width and height as the length and width. Subtract large openings such as windows or doors by calculating them separately and taking them off, or simply keep the waste allowance a little higher.
What if the store prices tile by the square foot?
Multiply the price per square foot by the square feet in one box (usually printed on the box) to get the price per box, then choose box pricing. Alternatively, multiply the price per square foot by one tile's area for a per-tile price.