How Much Tile for a 10x12 Room?
Tiles needed
65 tiles
120 square feet, 12 by 24 tile, an eighth inch joint, 8 tiles a box, 10 percent waste.
Anything 15 inches or longer counts as large format. The substrate has to be flat inside an eighth of an inch over ten feet, the notch goes up to half by half, and every tile gets back buttered for coverage. Offset the joints by a third at most, because a running bond half offset on a long plank telegraphs every bit of tile warp as lippage.
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How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Area to tile120 sq ft
- Tile width12 in
- Tile length24 in
- Tile thickness0.375 in
- Grout joint0.125 in
- Tiles per box8 each
- Waste allowance10 %
Tiles needed65 tiles
Anything 15 inches or longer counts as large format. The substrate has to be flat inside an eighth of an inch over ten feet, the notch goes up to half by half, and every tile gets back buttered for coverage. Offset the joints by a third at most, because a running bond half offset on a long plank telegraphs every bit of tile warp as lippage.
| Area with 10% waste | 132 sq ft |
|---|---|
| Coverage of one tile | 2.031 sq fttile plus one joint |
| Tiles per square foot | 0.49 |
| Boxes at 8 per box | 9 |
| Thinset, 50 lb bags | 4about 40 sq ft per bag at this tile size |
| Grout | 6.1 lbsold in 10 and 25 lb boxes |
| Backer board, 3 by 5 sheets | 8 |
The material list this produces
| Tile, boxes | 9 |
|---|---|
| Thinset mortar, 50 lb bags | 4 |
| Grout, lb | 7 |
| Tile spacers, each | 130 |
| Cement backer board, 3 x 5 sheets | 8 |
| Backer board screws, each | 320 |
Waste allowance compared
Waste is the only input here you choose rather than measure, and it is the one that decides whether the job finishes on a Saturday or on the following Saturday.
| Waste allowance | Tiles needed | Boxes at 8 per box |
|---|---|---|
| 5% | 63 tiles | 8 |
| 10% | 65 tiles | 9 |
| 15% | 68 tiles | 9 |
| 20% | 71 tiles | 9 |
What else matters here
One hundred and twenty square feet at 12 by 24 is 65 tiles with waste, 9 boxes. A room this shape is the easy case: four square corners, one doorway, and the cuts down one wall start the rows on the other.
Lay it so the cut row falls where it is least seen, which is usually against the wall the door does not face. Measure the room both ways first, because a room that is 10 feet at the door and 10 feet 2 at the far wall will put a tapered cut down one side and you want that taper hidden.
Four bags of thinset and 8 sheets of backer board. Stagger the board joints so they do not line up with the subfloor seams underneath, and leave an eighth of an inch between sheets for the thinset and tape.
What this calculator assumes
- The tile count is worked out from the space one tile actually occupies, which is the tile plus one grout joint on two sides, not the tile on its own. On a 12 by 24 with an eighth inch joint that difference is about one percent, and on a mosaic it is far more.
- 10 percent waste suits a straight lay in a square room. A diagonal or herringbone lay wastes 15, and a room full of jogs, niches and closets can reach 20.
- Grout is figured geometrically: the joint volume is the space around each tile times the tile thickness, converted at 105 pounds per cubic foot, which is where sanded grout lands once mixed. Manufacturer coverage charts vary, so treat this as the order quantity and not the gospel.
- Thinset coverage follows the trowel, and the trowel follows the tile: about 85 sq ft from a 50 lb bag with a quarter inch notch under small tile, 60 under 12 inch, and 40 under large format where the notch grows and the tile gets back buttered.
Questions people ask
How many square feet is a 10x12 room?
120 square feet. At 12 by 24 tile with an eighth inch joint that is 60 tiles bare and 65 once 10 percent waste is on it.
How much thinset does a bag cover?
It depends on the notch, and the notch follows the tile. A quarter by quarter square notch under small tile stretches a 50 pound bag across most of 85 square feet, a quarter by three eighths under a 12 inch tile gets about 60, and half by half under large format with back buttering is nearer 40. The bag states its own figure and that is the one that governs.
Should I buy extra tile?
Buy the whole job plus the waste in one order. Tile is fired in batches and the shade moves between batches, so a replacement box bought next spring will read as a patch from across the room. Keep the offcuts too, because a cracked tile three years from now is a lot easier to match from your own attic than from a supplier.
The tile calculator takes any dimensions you like and hands back the same list.