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 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% | 21 tiles | 3 |
| 10% | 22 tiles | 3 |
| 15% | 23 tiles | 3 |
| 20% | 24 tiles | 3 |
What else matters here
Five by eight is the standard American bathroom, tub across one end, and it 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 bathroom this size is all cuts. There is a toilet flange, a vanity, a door jamb and a tub deck in 40 square feet, and none of those cuts produce an offcut that starts another row.
Three sheets of cement board at 3 by 5, and set them in thinset rather than laying them dry. The screws hold the board down but the bed of thinset under it is what stops the floor flexing, and flex is what cracks grout in a bathroom.
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. Subtract nothing for the tub if the tub sits on the subfloor, because you tile up to it, not under it.
What size tile is best in a small bathroom?
Larger tile with fewer joints makes a small floor read bigger, and 12 by 24 is the common choice. The limit is how many cuts the room forces, because a big tile in a room full of obstacles throws away more of every tile you cut.
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.