BuildWellHow tile is estimated
Tile is estimated by the square foot and counted by the piece. Measure the area, work out how much floor or wall each tile takes up once its grout joint is counted, add waste for cuts and breakage, and divide.
For a floor, the area is length × width. For a wall, it’s the wall’s width times how high the tile goes. A shower is usually three walls: measure each, add them, and take out the opening for a niche or window only if it’s large.
The joint matters more than people expect. A 12 inch tile with a 1/8 inch joint takes up a 12⅛ inch square of floor, about 2% more than the tile itself. With small tiles and wide joints, the difference grows.
The tile formulas
- Area = length × width, in square feet.
- Each tile covers = (tile width + joint) × (tile length + joint) ÷ 144, in square feet.
- Tiles = area × (1 + waste) ÷ each tile’s coverage, rounded up.
- Thinset bags = area ÷ the bag’s coverage for your trowel, rounded up.
- Grout = area × the share of it that’s joint × the joint depth.
The share that’s joint is the difference between a tile’s cell and the tile, over the cell: for a 12 inch tile and a 1/8 inch joint, (12.125² − 12²) ÷ 12.125² = 2.05%. The joint is about as deep as the tile is thick. The calculator gives the result in quarts of mixed grout and cubic inches; grout bags list coverage by tile size and joint width, so compare against your bag’s chart and add extra for mixing and cleanup.
Tiles and grout per 100 square feet
| Tile | Joint | Tiles per 100 sq ft (with 10% waste) | Grout per 100 sq ft |
|---|---|---|---|
| 3 × 6 in | 1/16 in | 854 | 2.38 qt |
| 4 × 4 in | 1/16 in | 960 | 2.38 qt |
| 6 × 6 in | 1/8 in | 423 | 3.15 qt |
| 12 × 12 in | 1/8 in | 108 | 1.92 qt |
| 6 × 24 in | 1/8 in | 108 | 2.38 qt |
| 12 × 24 in | 1/8 in | 55 | 1.44 qt |
| 24 × 24 in | 1/8 in | 28 | 0.97 qt |
Small tiles need many more pieces and much more grout per square foot. A 3 × 6 subway wall uses about eight times the tiles of a 12 × 12 floor of the same size.
Thinset coverage by trowel
| Trowel notch | Typical coverage per 50 lb bag | Often used for |
|---|---|---|
| 1/4 × 1/4 in square | Roughly 90 sq ft | Small tile and mosaics |
| 1/4 × 3/8 in square | Roughly 60 sq ft | Tile around 12 in |
| 1/2 × 1/2 in square | Roughly 40 sq ft | Large-format tile |
These are typical figures printed on 50 lb bags. Products differ, so use your bag’s chart. The calculator uses these figures.
Coverage isn’t only about quantity. Industry installation standards call for at least 80% mortar contact under tile in dry areas and 95% in wet areas. Bigger tiles and uneven substrates need deeper notches, and large tiles are usually back-buttered as well. Pull up a tile now and then to check.
Worked examples
A 10 × 10 bathroom floor in 12 × 12 tile
100 square feet, a 1/8 inch joint, 3/8 inch thick tile and 10% waste. Each tile covers 1.0209 square feet, so 110 ÷ 1.0209 = 107.7: 108 tiles. With a 1/4 × 3/8 trowel at about 60 square feet a bag, 2 bags of thinset. The joints hold about 1.9 quarts of grout.
A shower in 3 × 6 subway tile
Three walls come to 60 square feet. With a 1/16 inch joint, 5/16 inch thick tile and 10% waste, each tile covers 0.1289 square feet: 512 tiles. One bag of thinset at about 90 square feet a bag with a 1/4 × 1/4 trowel, and about 1.4 quarts of grout. Backer board and waterproofing are separate.
A large-format floor
200 square feet of 24 × 24 tile with a 1/8 inch joint. Large tiles waste more per cut, so use 15%. Each tile covers 4.0418 square feet: 230 ÷ 4.0418 = 56.9, so 57 tiles. With a 1/2 × 1/2 trowel at about 40 square feet a bag, 5 bags of thinset. The joints are a small share of the floor, about 1.9 quarts of grout.
Grout: sanded or unsanded
Sanded grout is the usual choice for joints 1/8 inch and wider: the sand keeps it from shrinking and cracking in a wide joint. Unsanded grout is used for narrower joints, where sand wouldn’t pack in, and on surfaces sand could scratch. Some grouts are made for a range of widths; follow the bag.
Cement grouts are usually sealed after they cure. Other kinds may not need it. Price the sealing as part of the grout line if your grout calls for it.
Common mistakes
Counting tiles without the joint. It looks small, but on small tile the joint changes the count noticeably.
Too little waste on a pattern. Diagonal, herringbone and large tiles need more. Running short means waiting on a reorder that may not match.
Too shallow a trowel. Hollow spots under tile crack. Match the notch to the tile, back-butter large tiles, and check coverage.
Pricing walls like floors. Walls take longer, and showers need backer board and waterproofing first.
Forgetting trim and transitions. Edge trim, bullnose, thresholds and the caulk joint at corners and changes of plane are separate pieces and separate time.
From quantities to an estimate
A tile estimate also covers demolition, substrate prep, backer board, waterproofing, mixing and staging, setting, edge trim, grouting, sealing, caulking and cleanup.
Walls usually take longer per square foot than floors, and small tiles and mosaics longer than large ones, because there are more pieces to set and more joints to grout. Price the surface and the tile size, not only the area.
When you estimate a tile job in BuildWell, describe it by voice, text or photos and it plans each of those as its own line with labor hours. Materials are priced at stores near the job, checked within 30 days, and labor at your metro’s tile setter wage plus your overhead and markup. You can change any quantity, hour or price before you send it.
