A 12×10 ft floor (120 sq ft) needs 132 tiles of 12×12 or 66 tiles of 12×24, with 10% extra for cuts. To get boxes, divide by the tile count printed on the carton and round up — at 15 tiles per box, 132 tiles is 9 boxes. Run your own floor or wall in the free QtyLab tile calculator.
The tile formula
- Area = length × width (floor) or width × height (wall), in sq ft
- Add waste: area × 1.10 for 10%
- Sq ft per tile = tile width (in) × tile length (in) ÷ 144
- Tiles = area with waste ÷ sq ft per tile, rounded up
- Boxes = tiles ÷ tiles per box, rounded up
Worked example: 12×10 floor, 12×12 tile
- Area: 12 × 10 = 120 sq ft
- With 10% waste: 120 × 1.10 = 132 sq ft
- Tile size: 12 × 12 ÷ 144 = 1 sq ft per tile
- Tiles: 132 ÷ 1 = 132 tiles
- Boxes (example carton of 15): 132 ÷ 15 = 8.8 → 9 boxes
Same floor in 12×24 tile: 12 × 24 ÷ 144 = 2 sq ft per tile, so 132 ÷ 2 = 66 tiles.
How many boxes of tile do I need?
Box counts change from product to product, so always read the carton. It lists either tiles per box or sq ft per box. The table shows the same 12×10 floor with different carton sizes:
| Tile | Tiles needed | If the box holds… | Boxes to buy |
|---|---|---|---|
| 12×12 | 132 | 8 tiles | 17 |
| 12×12 | 132 | 10 tiles | 14 |
| 12×12 | 132 | 12 tiles | 11 |
| 12×12 | 132 | 15 tiles | 9 |
| 12×24 | 66 | 6 tiles | 11 |
| 12×24 | 66 | 8 tiles | 9 |
If the carton lists sq ft per box instead, divide your area with waste (132 sq ft here) by that number and round up. Buy every box from the same lot so the shade matches.
Tiles per 100 square feet
All counts include 10% waste. Click a size to open it in the calculator.
| Tile size | Sq ft per tile | Tiles for 100 sq ft |
|---|---|---|
| 3×6 subway | 0.125 | 880 |
| 4×4 | 0.11 | 990 |
| 6×6 | 0.25 | 440 |
| 12×12 | 1 | 110 |
| 12×24 | 2 | 55 |
| 18×18 | 2.25 | 49 |
| 24×24 | 4 | 28 |
Tiles by floor size
10% waste, rounded up to whole tiles.
| Floor (ft) | Area | 12×12 tiles | 12×24 tiles | 18×18 tiles | 24×24 tiles |
|---|---|---|---|---|---|
| 5×8 bathroom | 40 sq ft | 44 | 22 | 20 | 11 |
| 10×10 | 100 sq ft | 110 | 55 | 49 | 28 |
| 12×10 | 120 sq ft | 132 | 66 | 59 | 33 |
| 12×12 | 144 sq ft | 159 | 80 | 71 | 40 |
| 15×20 | 300 sq ft | 330 | 165 | 147 | 83 |
How much extra tile to buy
| Layout | Waste to add |
|---|---|
| Straight grid, simple room | 10% |
| Diagonal, herringbone, or lots of cuts | About 15% |
| Large-format tile in a small, cut-heavy room | Lean toward 15% |
| QtyLab default | 10% |
Waste covers edge cuts and breakage, and leaves a few spares from the same lot for future repairs. Running short mid-job often means a shade that does not match.
Common tile estimating mistakes
- Counting tiles, not boxes — stores sell whole cartons, so round the box count up.
- Assuming every box holds the same count — two 12×12 products can pack very differently.
- Skipping waste on a diagonal or herringbone layout — those patterns cut more tile.
- Mixing lots — buy all boxes at once and check the lot number.
- Measuring the room but not the closets or alcoves that get tiled too.
Shopping list for a 12×10 floor (12×12 tile)
- 132 tiles (9 boxes if the carton holds 15) — compare 12×12 floor tile
- Thinset mortar for about 132 sq ft — check the bag’s coverage chart for your trowel notch; shop thinset
- Grout for about 120 sq ft of 12×12 tile — coverage depends on joint width, so use the chart on the bag; shop grout
- 1 notched trowel sized for your tile — shop notched trowels
- 1 bag of tile spacers and a leveling system — shop spacers and leveling clips
- 1 tile cutter or wet saw, plus a grout float and sponge — shop tile cutters
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Related guides and calculators
- Redoing the bathroom walls first? How many drywall sheets do I need and the drywall calculator.
- Painting the rest of the room: how many gallons of paint you need.
- All guides: QtyLab guides.
Frequently asked questions
How many boxes of tile do I need?
Divide the tiles you need by the number of tiles in one box and round up. A 120 sq ft floor in 12×12 tile with 10% waste needs 132 tiles; at 15 tiles per box that is 9 boxes. Box counts vary by product, so read the carton.
How many 12×12 tiles do I need for 100 square feet?
110 tiles. A 12×12 tile covers 1 sq ft, and 100 sq ft plus 10% waste is 110 sq ft.
How many 12×24 tiles do I need for 100 square feet?
55 tiles. A 12×24 tile covers 2 sq ft, so 110 sq ft (100 plus 10% waste) ÷ 2 = 55.
How much extra tile should I buy?
Plan on 10% extra for a straight grid in a simple room and about 15% for diagonal, herringbone, or cut-heavy layouts. Keep a few spares from the same lot for repairs.
How do I convert tile size to square feet?
Multiply the tile’s width by its length in inches and divide by 144. A 12×24 tile is 288 ÷ 144 = 2 sq ft; an 18×18 tile is 324 ÷ 144 = 2.25 sq ft.