Tile Calculator
Work out how many tiles and boxes you need for a floor, wall or backsplash, including a waste allowance.
Free · No sign-up · Runs in your browser · Last reviewed November 2026
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About the Tile Calculator
Buying tile is easier when you know the exact count. This tile calculator divides the area by the size of one tile and adds a waste allowance for cuts, breakage and future repairs. It then converts the tile count into boxes and estimates the cost. Use 10% waste for straight layouts and 15% or more for diagonal or herringbone patterns.
How to use it
- Enter the length and width of the area in feet.
- Enter the tile width and length in inches and the waste percentage.
- Enter tiles per box and the price per box, then press Calculate tile.
Tile formula
Tiles = area ÷ area of one tile × (1 + waste). A 12 × 10 ft floor is 120 sq ft. A 12 × 24 inch tile covers 2 sq ft, so you need 60 tiles, or 66 with 10% waste.
Recommended waste allowance
| Layout | Waste |
|---|---|
| Straight grid | 10% |
| Diagonal | 15% |
| Herringbone or mosaic | 15% to 20% |
| Large-format tile | 10% to 15% |
Buying tips
- Buy all tiles from the same dye lot.
- Keep a few spare tiles for future repairs.
- Measure each wall or floor section separately and add them.
Tile tips for backsplashes and tricky layouts
A different scenario: a kitchen backsplash 10 ft long and 1.5 ft tall is 15 sq ft. A 3 × 6 inch subway tile covers 0.125 sq ft, so the exact count is 120. Adding 10% gives 132 tiles, which is 3 boxes if each holds 50. Cutting around outlets and windows is where small jobs lose tiles.
Mistakes to avoid
- Using tile sizes without grout joints. Nominal sizes can differ from actual sizes, so use the dimension printed on the box when you can.
- Ignoring shade variation. Boxes from different production runs can look different, so buy everything at once and mix tiles from several boxes as you lay them.
- Forgetting setting materials. Thinset, grout, backer board and sealer are separate purchases.
- Not planning the layout. Dry-fit a row first so that edge tiles are not left as thin slivers.
For hardwood, laminate or vinyl floors, use the flooring calculator instead.
Frequently asked questions
How many tiles do I need for 100 square feet?
With 12 by 12 inch tiles and 10% waste you need 110 tiles, or 11 boxes of 10.
How much extra tile should I buy?
Ten percent for simple layouts and 15% or more for diagonal or complex patterns.
How do I calculate tiles for a wall?
Multiply wall height by width, subtract windows and doors, then use the same formula.
Does grout line width change the count?
Slightly. For a precise count use the tile size plus the grout joint.
Why buy from the same dye lot?
Color and shade can vary between production runs, which shows up on a finished floor.
Should I buy extra tile even if my layout is simple?
Yes. Keeping a box or at least several spare tiles lets you fix a crack later, since a discontinued pattern or different dye lot may not match.
How do I find the area of an L-shaped or odd room?
Divide it into rectangles, multiply length by width for each, and add them. Run the tile calculator once on the total or once per section if tile sizes differ.
Last reviewed: November 2026.