Tile Calculator
Square feet, tile count, and thinset for floors and walls.
10% for straight layouts, 15% for diagonal or herringbone.
You need
88 sq ft
Round up to whole boxes using the coverage printed on the box.
- Tile count
- 88 tiles
- Thinset (50 lb bags)
- 2 bags
- Floor area
- 80 sq ft
Estimates only. Verify quantities before ordering.
How this is calculated
Area to buy = length x width x (1 + waste %). Tile count = area in sq in / tile area in sq in, rounded up. Thinset assumes one 50 lb bag per 75 sq ft with a 1/4 inch notch trowel; larger tile and uneven floors use more.
Enter the area and pick a tile size, and this calculator returns the square footage to buy, the piece count, and the thinset to set it. Tile is sold by the box with coverage printed on the label, so the primary number to carry to the store is square feet including waste; the piece count is a sanity check.
Waste matters more with tile than with most flooring because every cut piece at a wall is unusable on the opposite side. Use 10% for a straight lay in a simple room. Go to 15% for diagonal layouts, herringbone, large-format tile in small rooms, or any room with lots of jogs and pipes to cut around.
Tile for common room sizes
Rows assume 12 x 12 in tile with 10% waste and thinset at one 50 lb bag per 75 sq ft.
| Room size | Sq ft to buy | Tiles | Thinset |
|---|---|---|---|
| 5 x 8 ft (bathroom) | 44 sq ft | 44 tiles | 1 bags |
| 8 x 10 ft | 88 sq ft | 88 tiles | 2 bags |
| 10 x 10 ft | 110 sq ft | 110 tiles | 2 bags |
| 12 x 10 ft (kitchen) | 132 sq ft | 132 tiles | 2 bags |
| 15 x 12 ft | 198 sq ft | 198 tiles | 3 bags |
Porcelain, ceramic, and natural stone
Porcelain is denser and less absorbent than standard ceramic, which is why it is specified for floors, wet areas, and anywhere outdoors that freezes. It is harder to cut and drill for the same reason. Ceramic is softer, cheaper, and entirely adequate for walls and light-duty floors, and it scores and snaps more easily on a manual cutter.
Natural stone, marble, travertine, slate, and granite, is porous and needs sealing, often before grouting as well as after. It also varies in thickness and color from piece to piece, so it wants to be dry-laid and sorted before setting. Budget more time and more waste for stone than for a manufactured tile of the same nominal size.
For floors, check the PEI rating and the coefficient of friction rather than choosing on appearance alone. A wall tile used on a floor wears through its glaze, and a polished tile in an entry or a bathroom is genuinely dangerous when wet. Rectified tiles, which are machine-trimmed to an exact size, allow very narrow grout lines but demand a flatter substrate and less forgiveness in the layout.
Thinset, grout, and how much of each
Modified thinset suits most installations; unmodified is specified over certain membranes and for some porcelain applications, so follow the membrane manufacturer rather than habit. Large-format tile, anything over about 15 inches on a side, needs a large-and-heavy-tile mortar rather than standard thinset, because ordinary thinset shrinks too much across that span and leaves voids.
Coverage is governed by the trowel notch, which is governed by tile size. A quarter inch square notch under a small tile covers far more area per bag than a half inch notch under large format, so a 50 lb bag might cover 80 to 95 square feet in one case and 40 to 50 in another. Read the bag against the notch size you will actually use rather than assuming an average.
Grout choice follows joint width. Unsanded grout is for joints under about an eighth of an inch, sanded for wider joints because the sand resists shrinkage cracking. Epoxy grout costs considerably more, is harder to work before it sets, and is worth it in showers and kitchens because it does not absorb stains or need sealing.
Layout, waste, and the substrate underneath
Ten percent waste covers a straight layout on a square room. Diagonal layouts and herringbone push that toward 15 percent because every perimeter tile is cut, and large-format tile in a small room can exceed that again since a single bad cut wastes a large piece. Buy the whole job in one shade lot and keep a box back for future repairs, since tile lines are discontinued constantly.
Plan the layout from the center outward so that the cut tiles at opposite walls are equal, and shift the starting line if that would leave a sliver at a prominent edge. Snap lines and dry-lay a row in both directions before mixing any mortar. Ten minutes here decides whether the finished floor looks deliberate or accidental.
The substrate matters more than any of it. Tile is rigid and cracks over deflection, so a floor needs to be flat within about an eighth of an inch over 10 feet and stiff enough for the tile type, which usually means cement board or an uncoupling membrane over a properly built subfloor. Tiling directly over a springy floor or over old vinyl is the most common reason a job fails within a year.
Common questions
How much extra tile should I buy?
10% beyond the measured area for straight layouts, 15% for diagonals and patterns. Also keep a few spare tiles after the job: dye lots vary between production runs, and a matching repair tile years later is worth far more than what the spares cost.
How much thinset do I need?
With a 1/4 inch square-notch trowel, a 50 lb bag sets roughly 75 to 85 square feet of small and mid-size tile. Large-format tile needs a deeper 1/2 inch notch and back-buttering, which can cut a bag's coverage to 40 or 50 square feet, so buy accordingly.
Do I need to worry about tile lippage with large tile?
Tiles 12 x 24 and larger are slightly bowed from firing, so offsets over 33% create visible lips between pieces. Use a maximum 1/3 offset for large-format tile, a medium-bed mortar, and a leveling-clip system if the substrate is not dead flat.
Does the subfloor matter for tile?
More than the tile does. Tile needs a stiff, flat base: cement board or an uncoupling membrane over wood subfloors, with deflection within L/360. Tile installed straight over a bouncy or flexing floor cracks at the grout lines no matter how good the tile is.