How Much Tile for a 5x8 Bathroom Floor?
Tiles needed
23 tiles
40 square feet, 12 by 24 tile, an eighth inch joint, 8 tiles a box, 15 percent waste for a cut up room.
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 tile40 sq ft
- Tile width12 in
- Tile length24 in
- Tile thickness0.375 in
- Grout joint0.125 in
- Tiles per box8 each
- Waste allowance15 %
Tiles needed23 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 15% waste | 46 sq ft |
|---|---|
| Coverage of one tile | 2.031 sq fttile plus one joint |
| Tiles per square foot | 0.49 |
| Boxes at 8 per box | 3 |
| Thinset, 50 lb bags | 2about 40 sq ft per bag at this tile size |
| Grout | 2 lbsold in 10 and 25 lb boxes |
| Backer board, 3 by 5 sheets | 3 |
The material list this produces
| Tile, boxes | 3 |
|---|---|
| Thinset mortar, 50 lb bags | 2 |
| Grout, lb | 3 |
| Tile spacers, each | 46 |
| Cement backer board, 3 x 5 sheets | 3 |
| Backer board screws, each | 120 |
Waste allowance compared
Waste follows the layout: ten percent for a straight lay, fifteen for a diagonal or a cut up bathroom, twenty for herringbone.
| Waste allowance | Tiles needed | Boxes at 8 per box |
|---|---|---|
| 5% | 21 tiles | 3 |
| 10% | 22 tiles | 3 |
| 15% | 23 tiles | 3 |
| 20% | 24 tiles | 3 |
What else matters here
A five by eight bathroom is 40 square feet of floor. At 12 by 24 that is 20 tiles bare and 23 with waste, which is 3 boxes.
Fifteen percent rather than ten, because a cut up bathroom wants fifteen. A room with a doorway jog and a tub deck is fifteen even on a straight lay, because the cuts stop repeating and nothing fits anywhere twice.
Three sheets of cement board at 3 by 5, the sheet size the calculator figures.
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 5x8 bathroom?
40 square feet of floor.
How much waste should I add?
Ten percent for a straight lay in a square room, fifteen for a diagonal or a cut up bathroom, twenty for herringbone. Under ten leaves nothing for a bad box or a broken tile, and both happen.
The tile calculator takes any dimensions you like and hands back the same list.