How Much Grout for 150 Square Feet of Tile?
Grout
8.4 lb
150 square feet of 12 by 12 tile, an eighth inch joint, tile five sixteenths thick.
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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 tile150 sq ft
- Tile width12 in
- Tile length12 in
- Tile thickness0.3125 in
- Grout joint0.125 in
- Tiles per box15 each
- Waste allowance10 %
Tiles needed162 tiles
| Area with 10% waste | 165 sq ft |
|---|---|
| Coverage of one tile | 1.021 sq fttile plus one joint |
| Tiles per square foot | 0.98 |
| Boxes at 15 per box | 11 |
| Thinset, 50 lb bags | 3about 60 sq ft per bag at this tile size |
| Grout | 8.4 lbsold in 10 and 25 lb boxes |
| Backer board, 3 by 5 sheets | 10 |
The material list this produces
| Tile, boxes | 11 |
|---|---|
| Thinset mortar, 50 lb bags | 3 |
| Grout, lb | 9 |
| Tile spacers, each | 324 |
| Cement backer board, 3 x 5 sheets | 10 |
| Backer board screws, each | 400 |
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 15 per box |
|---|---|---|
| 5% | 155 tiles | 11 |
| 10% | 162 tiles | 11 |
| 15% | 169 tiles | 12 |
| 20% | 177 tiles | 12 |
What else matters here
Eight and a half pounds, which is one small bag. Grout is worked out here as geometry rather than read off a chart: the volume of the joints around every tile, times the tile thickness, at 105 pounds a cubic foot.
That is why three separate numbers move it. A wider joint moves it, obviously. A thicker tile moves it, because the joint is deeper. And a smaller tile moves it most of all, because a small tile puts far more linear joint into every square foot. The same 150 feet in 3 by 6 subway would want roughly five times this.
Buy the whole job in one bag where you can, and mix it in one batch if the floor is going down in one day. Grout color is pigment in cement, and two batches of the same product mixed to different consistencies dry visibly different shades.
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 pounds of grout per square foot?
For 12 by 12 tile at an eighth inch joint, about 0.056 pounds a square foot. For 12 by 24 it is lower, around 0.05. For a small mosaic it can be five times that. The tile size is what drives it.
Sanded or unsanded grout?
Sanded for joints of an eighth of an inch and wider, unsanded below that. Sanded grout in a very narrow joint will not pack, and unsanded grout in a wide joint shrinks and cracks as it cures.
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.