Tile Calculator
Enter the area and the coverage printed on the box. You get square footage with waste, the number of boxes to order, and how many individual tiles that works out to.
How the tile calculator works
- Area = length × width, in square feet. For an L-shaped room, split it into rectangles and add them.
- Add waste — 5% for a plain square room, 10% for a standard layout, 15% for diagonal or heavily cut spaces.
- Boxes = area with waste ÷ the square footage printed on the box, rounded up.
- Tiles = area with waste ÷ the area of one tile. A 12×12 tile is 1 sq ft; a 24×24 tile is 4 sq ft.
Worked example
A 10 ft × 12 ft bathroom floor with 24×24 in tiles and 10% waste:
- 10 × 12 = 120 sq ft
- 120 × 1.10 = 132 sq ft to buy
- 132 ÷ 10 sq ft per box = 13.2 → 14 boxes
- Each tile is 4 sq ft, so 132 ÷ 4 = 33 tiles
Order 14 boxes and keep the spare one unopened. The extra 12 sq ft is your insurance against a cracked tile in three years.
Waste allowance by layout
| Layout | Waste | Why |
|---|---|---|
| Square room, straight grid | 5% | Few cuts, minimal breakage |
| Typical room, straight lay | 10% | Perimeter cuts and doorways |
| Diagonal / herringbone | 15% | Every edge tile is a cut |
| Many obstacles, small tiles | 15–20% | Toilets, pipes, niches |
Tile count by size
| Tile size | Area per tile | Tiles per 100 sq ft |
|---|---|---|
| 12 × 12 in | 1.00 sq ft | 100 |
| 12 × 24 in | 2.00 sq ft | 50 |
| 18 × 18 in | 2.25 sq ft | 45 |
| 24 × 24 in | 4.00 sq ft | 25 |
| 3 × 6 in subway | 0.125 sq ft | 800 |
Grout lines are not subtracted. For large-format tile with 1/8 inch joints the difference is negligible; for small mosaic the joints are already part of the sheet.
Frequently asked questions
How much tile waste should I allow?
10% for a standard straight lay, 15% for diagonal or herringbone patterns, and 15–20% where there are many cuts around fixtures. Five percent only works in a simple square room.
How many 12x12 tiles are in a square foot?
Exactly one. A 12×12 inch tile is 1 sq ft, so 100 tiles cover 100 sq ft before waste.
How many boxes of tile do I need for 100 square feet?
Divide 110 sq ft (100 plus 10% waste) by the coverage on the box. At 10 sq ft per box that is 11 boxes; at 15 sq ft per box it is 8.
Should I buy an extra box?
Yes — buy one box more than the minimum and leave it sealed. Dye lots change between production runs, and a repair two years from now will not match without a spare from the same lot.
Does this include grout or thinset?
No. Thinset runs about 1 bag of 50 lb per 50–60 sq ft with a 1/2 inch trowel, and grout depends on joint width and tile size — roughly 1 lb per 10 sq ft for 12×12 tile with 1/8 inch joints.