How to calculate how many tiles you need
Tile math is floor area ÷ tile area, with waste added. Measure the length and width of the floor in feet and multiply for square footage. Then work out the area of a single tile in square feet, divide, and round up.
- Floor area = length (ft) × width (ft)
- Tile area = tile width (in) × tile height (in) ÷ 144
- Tiles = (floor area × (1 + waste%)) ÷ tile area, rounded up
Dividing the tile's inch dimensions by 144 converts square inches to square feet, so both sides of the division use the same units.
The tiling mistake that leaves an ugly sliver
Start tiling tight against one wall and you'll almost always finish the run with a skinny, awkward sliver of tile on the far side — and it's the first thing everyone notices. Pros find the center of the room, dry-lay from there, and let both ends finish with the same balanced cut.
Knowing your total square footage — and ordering about 10% extra for cuts — means you can lay out from the center without running short mid-job.
Pro move: dry-lay a full row before you mix any thinset. Five minutes of planning saves a wall full of slivers.
How much waste should you add for tile?
| Layout | Recommended waste |
|---|---|
| Straight, simple rectangular room | 10% |
| Lots of corners, niches or fixtures | 12–15% |
| Diagonal or herringbone pattern | 15% |
| Large-format tile (24 in and up) | 15%+ |
Buying an extra box also gives you matching spares for repairs years later, when the same dye lot may be gone.
How many 12×12 tiles in a square foot?
A 12×12-inch tile is exactly one square foot, so the tile count roughly matches the square footage plus waste. Smaller tiles — like 6×6 — take four per square foot, while larger ones cover more ground each. The calculator handles any size you enter.
Tile calculator FAQ
- Does this work for wall tile too?
- Yes. Enter the wall's height and width in place of length and width, and the math is the same. Add up multiple walls if you're tiling more than one.
- How much grout will I need?
- Grout depends on tile size and joint width, but a 25-lb bag of sanded grout typically covers 100–200 sq ft for standard floor tile. Tight joints and large tiles use less.
- Should I buy tile from the same lot?
- Yes — color can shift slightly between production runs. Buy all your tile, including the waste allowance, at once so it all matches.