Tile Calculator
Works for floor tile, wall tile and backsplashes. Enter the area you're tiling and your tile size to get the number of tiles and boxes, with a waste allowance for your layout — then size the thinset and grout with the related calculators.
Results
How the tile calculator works
Tile is estimated by area. The number of tiles per square foot comes straight from the tile's nominal size — a 12 × 12 inch tile covers exactly one square foot, a 12 × 24 covers two, a 3 × 6 subway tile takes eight to the square foot. The calculator multiplies your area by the tiles-per-square-foot, adds a waste allowance for cuts, and rounds up to whole tiles.
Formula: tiles per sq ft = 144 ÷ (tile width × height in inches), then area × (1 + waste%) × tiles per sq ft = tiles (rounded up)
| Tile size | Tiles / sq ft |
|---|---|
| 2 × 2 in mosaic | 36 |
| 4 × 4 in | 9 |
| 3 × 6 in subway | 8 |
| 6 × 6 in | 4 |
| 12 × 12 in | 1.0 |
| 18 × 18 in | 0.44 |
| 12 × 24 in | 0.5 |
| 24 × 24 in | 0.25 |
Nominal sizes already build in the small grout joint between tiles, so you don't subtract for grout lines when counting. If your tile is an odd size, type its actual width and height into the custom boxes and the calculator recomputes the per-square-foot figure.
Waste, boxes and what else you'll need
- Add 10% for a standard straight layout, 15% for a diagonal, and 20% for herringbone, chevron or a busy room with lots of cuts. Long, narrow planks and large-format tile waste more at the edges.
- Tile is sold by the box. Enter the box coverage (printed on the box) and the calculator rounds up to whole boxes, since that's what you'll actually buy and pay for.
- Keep at least one unopened box after the job — dye lots shift between runs, so a discontinued line is impossible to match for a future repair.
- Tiles are only part of the order: you'll also need thinset to set them and grout for the joints, plus spacers and a trowel. Size the thinset with the calculator linked below.
Frequently asked questions
How many tiles do I need for a 100 square foot floor?
With 12 × 12 inch tiles (one per square foot) and a 10% straight-lay waste allowance, a 100 sq ft floor needs 110 tiles. Larger 12 × 24 tiles would need 55, and 6 × 24 planks 110.
How do I calculate how many tiles I need?
Work out the area (length × width), add a waste allowance — 10% straight, 15% diagonal, 20% herringbone — then multiply by the tiles per square foot, which is 144 divided by the tile's width times height in inches. Round up to whole tiles, and to whole boxes if buying by the box.
How much extra tile should I buy for waste?
Add 10% for a straight layout, 15% for diagonal, and up to 20% for herringbone or a cut-heavy room. Buy at least one extra box beyond that as well, so a cracked tile years later still matches your dye lot.
Do I subtract grout lines when counting tiles?
No. A tile's nominal size — the "12-inch" tile — already accounts for the typical grout joint, so the tiles-per-square-foot figure is correct as-is. You only enter a custom size if your tile's actual dimensions differ from the standard nominal sizes.