This floor tile calculator counts how many tiles to buy for a rectangular floor, and how many boxes that is. Enter the room in feet, the tile in inches, the grout joint in inches, a waste allowance, and the number of tiles in a box. The sample is a 10 by 12 foot floor, 12 inch square tiles, a 1/8 inch joint, 10% waste, and 10 tiles in a box. The headline is 130 tiles. That is not the same question as the room paint calculator, which turns wall area into gallons, and it is not the concrete calculator, which turns a slab thickness into cubic yards.
The grout joint is added once to the tile length and once to the tile width. Each tile in a grid is responsible for the joint on two edges, and the tiles at the opposite walls are cut into the remaining space. A 12 inch tile with a 1/8 inch joint therefore covers 12.125 by 12.125 inches, which is 1.0209 square feet, not a neat 1 square foot. Ignoring the joint on this sample buys two extra tiles. The waste allowance is a separate percentage for cuts, breakage, and a tile kept back for a later repair. Diagonal layouts and tiles with a pattern that has to be matched need more waste than a straight grid. The form will not guess that. You type the percentage.
How to use this calculator
- Enter the floor length and width in feet. The sample is 10 by 12, which is 120 square feet. Measure the floor you will tile, not the room including a closet you are leaving bare.
- Enter the tile length and width in inches. The sample is 12 by 12. A rectangular tile uses both fields. A 12 by 24 tile is 12 in one field and 24 in the other.
- Enter the grout joint in inches. The sample, 0.125, is 1/8 inch. Use 0 if you are estimating without a joint. Then enter a waste allowance from 0 to 100 percent. The sample is 10.
- Enter how many tiles are in the box you will actually buy. The sample is 10. Press Calculate. The headline is the waste-adjusted tile count, rounded up. Boxes, the no-waste count, and any spare tiles in the last box appear underneath.
How the tile count is rounded up
Floor area is length times width, in square feet. The sample is 10 times 12, which is 120. Coverage of one tile is (tile length plus grout) times (tile width plus grout), divided by 144, because a square foot is 144 square inches. For a 12 inch tile and a 0.125 inch joint that product is 12.125 times 12.125, which is 147.015625 square inches, and 147.015625 divided by 144 is 1.0209418 square feet. The calculator displays that coverage as 1.0209 square feet. The waste allowance is applied to the floor area before the division. Ten percent of 120 is 12, so the area to cover is 132 square feet. Dividing 132 by the full-precision coverage gives 129.29 tiles before rounding. The count to buy is the next whole tile, 130.
Boxes are the tile count divided by the number in a box, rounded up. The sample’s 130 tiles in boxes of 10 are 13 boxes, and the last box is full. There is no spare tile. Skip the waste allowance and the same floor needs 118 tiles, which is 12 boxes. The joint is why 118 is not 120. A 12 inch tile with no grout covers exactly 1 square foot, so 120 square feet plus 10% waste is 132 tiles exactly, and 132 tiles in boxes of 10 round up to 14 boxes with 8 spare. Adding the 1/8 inch joint drops the buy from 132 tiles to 130 and drops the boxes from 14 to 13. The joint is not a reason to skip waste. It is a reason not to pretend each tile covers a full square foot.
A 12 by 24 inch tile on the same 10 by 12 floor, with the same 1/8 inch joint and 10% waste, covers 2.0314 square feet. The unrounded count is 64.98, so the headline is 65 tiles. In boxes of 8 that is 9 boxes, and the last box leaves 7 spare. Without waste the count is 60 tiles, which is 8 boxes exactly. The waste allowance, not the rounding, is what opens the ninth box. A 6 by 6 inch tile is the other direction. On an 8 by 10 foot floor, which is 80 square feet, a 1/8 inch joint gives 0.2605 square feet per tile. Fifteen percent waste lifts the area to 92 square feet and the unrounded count to 353.13, so you buy 354 tiles. In boxes of 24 that is 15 boxes, with 6 spare. Without waste the count is 308 tiles and 13 boxes. Small tiles multiply both the cut waste and the chance that a box count is decided by a fraction.
A 5 by 5 foot floor with 12 inch tiles, a 1/8 inch joint, and no waste at all still does not land on a whole number of tiles. Coverage is 1.0209 square feet, 25 divided by that coverage is 24.49, and the calculator rounds up to 25 tiles. Three boxes of 10 leave 5 spare. The round-up is the difference between 24.49 and a tile you can buy. It is not a hidden waste percentage. If you also type 10% waste, you are adding waste on top of that round-up, which is what the sample does. The detail line “tiles before rounding up” is the figure to read when you want to see how close the fraction was.
Formula
Floor area (sq ft) = length in feet × width in feet Coverage of one tile (sq ft) = (tile length in inches + grout) × (tile width in inches + grout) / 144 Area with waste = floor area × (1 + waste percent / 100) Tiles before rounding = area with waste / coverage Tiles to buy = area with waste / coverage, rounded up to the next whole tile Tiles with no waste = floor area / coverage, rounded up Boxes = tiles to buy / tiles per box, rounded up Spare tiles = boxes × tiles per box − tiles to buy A grout joint of 0 leaves coverage equal to the face of the tile.
The sample’s 129.29 uses the full coverage of 1.0209418 square feet, then the display rounds that quotient to two decimal places. Multiplying the displayed 1.0209 by 129.29 will not return 132 exactly. The tile you buy is the rounded-up 130, not the 129.29. The same display rule turns a no-grout coverage of exactly 1 square foot into the line “1 sq ft” rather than “1.0000 sq ft.”
Rounding up happens twice, and the two rounds are not the same decision. Tiles round up so you do not stop a fraction of a tile short of the waste-adjusted area. Boxes round up so you do not leave the store one tile short of that tile count. On the 12 by 24 example, 64.98 tiles become 65, and 65 divided by 8 becomes 9 boxes. Buying 8 boxes would be 64 tiles, one short of the rounded tile count and more than one short of a job that also breaks a tile. The spare-tile line tells you how many of the last box you did not need for the count. It does not promise those tiles will be the right ones for a future repair if the dye lot changes.
Worked floor tile examples
10 by 12 feet, 12 inch tiles, 1/8 inch joint, 10% waste
The calculator shows 130 tiles. Floor area is 120 sq ft. Coverage is 1.0209 sq ft. The area with 10% waste is 132 sq ft. Tiles before rounding up are 129.29. Tiles with no waste allowance, rounded up, are 118. Boxes to buy are 13 boxes of 10. Boxes if you skip the waste allowance are 12. The last box is full.
Set the grout joint to 0 and keep everything else. Coverage becomes 1 sq ft, the unrounded count becomes 132, and the headline becomes 132 tiles, which is 14 boxes with 8 spare. The joint saved two tiles and one box on this particular floor. It will not save a box on every floor. A count of 121 tiles with a joint and 120 without would still be 13 boxes of 10 either way. Read the box line, not just the tile line, when the box is what you pay for.
The same floor in 12 by 24 inch tiles
Tile length 12, tile width 24, grout 0.125, waste 10, and 8 tiles per box. The calculator shows 65 tiles. Coverage is 2.0314 sq ft. Tiles before rounding up are 64.98. Without waste the rounded count is 60. Boxes to buy are 9 boxes of 8, and the spare in the last box is 7. Skipping waste would be 8 boxes exactly.
The floor did not change. The tile did. 130 of the 12 inch squares and 65 of the 12 by 24 rectangles are not a coincidence of the waste percentage. The larger tile covers almost twice the area, 2.0314 against 1.0209, and 130 divided by that ratio is about 65. The box size changed too, from 10 to 8, so the spare tiles are not comparable. A store that sells the rectangle in boxes of 10 would show a different box count for the same 65 tiles. Type the count printed on the box you are holding.
Small mosaics, and a floor that is already a fraction
An 8 by 10 foot floor is 80 square feet. Six inch tiles, a 1/8 inch joint, 15% waste, and 24 tiles per box produce 354 tiles. Coverage is 0.2605 sq ft. The area with waste is 92 sq ft, and the unrounded count is 353.13. Without waste the rounded count is 308 tiles, which is 13 boxes. With waste it is 15 boxes, and 6 tiles in the last box are spare. Fifteen percent is a judgment for cuts around a toilet, a vanity, and a closet. A clear rectangular floor often does not need that much. The form accepts it because you typed it. It does not know the room has fixtures.
A 5 by 5 foot closet, 12 inch tiles, a 1/8 inch joint, and 0% waste shows 25 tiles from an unrounded 24.49. Three boxes of 10 leave 5 spare. The round-up from 24.49 to 25 is the only extra. If the closet door eats a tile’s worth of cuts, 0% waste is the assumption that fails, not the coverage formula. Raise the waste field. Do not stretch the room dimensions to hide the cuts, because that also stretches the open floor that did not need a cut.
Tile counts for rectangular floors
| Floor | Tile | Grout | Waste | Tiles | Boxes | Tiles, no waste |
|---|---|---|---|---|---|---|
| 10 × 12 ft | 12 × 12 in | 0.125 | 10% | 130 | 13 of 10 | 118 |
| 10 × 12 ft | 12 × 12 in | 0 | 10% | 132 | 14 of 10 | 120 |
| 10 × 12 ft | 12 × 24 in | 0.125 | 10% | 65 | 9 of 8 | 60 |
| 8 × 10 ft | 6 × 6 in | 0.125 | 15% | 354 | 15 of 24 | 308 |
| 5 × 5 ft | 12 × 12 in | 0.125 | 0% | 25 | 3 of 10 | 25 |
What a rectangular tile count leaves out
The floor is a rectangle. A bay window, a diagonal closet, and an L-shaped room are two rectangles added together, or a sketch you measure yourself. The form will not subtract an island you are tiling around. Measure the floor that receives tile, including the area under a future appliance if you will tile there, and leave out the area you will not. Niches and shower floors are separate small counts. Mixing them into the room length overstates the field tile and still does not count the niche.
The grout model is a straight grid. A herringbone or a diagonal layout cuts more tiles, and a pattern with a repeat has to finish on the repeat, not merely cover the square footage. Raise the waste allowance for those layouts. Ten percent is a common starting figure for a straight set with ordinary cuts. It is not a rule. Tiles sold by the piece, rather than by the box, still use the tile headline. Set the box size to 1 if you want the box line to match the tile line. A box size of 10 when the shelf pack is 16 will tell you to buy the wrong number of cartons.
Nothing in the formula knows the thickness of the tile, the thinset under it, or the grout you need in pounds. Coverage here is the face of the tile plus the joint, which is the count of pieces. A bag of grout is sold against joint width, joint depth, and the linear feet of joint, which this page does not compute. A meter-measured room has to be converted to feet first. The length converter on this site turns metres into feet. It does not know that a 30 centimetre European tile is 11.81 inches rather than 12. Type the inches printed on the carton.
Rounding up can leave a nearly full spare box when the unrounded count is just over a box boundary. The 64.98 tile example becomes 65 and then 9 boxes, with 7 spare. If you are willing to use the waste allowance as the cushion and the unrounded count is only a hundredth over a whole tile, you might decide not to buy the extra box. That is a judgment about breakage. The headline still rounds up, because the calculator cannot see the tiles you already broke in the driveway.
Frequently asked questions
How many 12 inch tiles do I need for a 10 by 12 foot floor?
With a 1/8 inch grout joint and 10% waste, this calculator shows 130 tiles, which is 13 boxes of 10. The floor is 120 square feet, one tile covers 1.0209 square feet once the joint is included, and 132 square feet with waste comes to 129.29 tiles before rounding up. Without the waste allowance the rounded count is 118 tiles, or 12 boxes.
Does the floor tile calculator count the grout joint as part of the tile?
Yes. The joint is added to the length and the width before the area is divided by 144. A 12 inch tile with a 1/8 inch joint covers 1.0209 square feet, not 1. Set the joint to 0 and the same 10 by 12 floor with 10% waste needs 132 tiles instead of 130. The joint is not a substitute for the waste percentage. Waste is a separate field for cuts and breakage.
Why does a 12 by 24 tile on that floor need 65 tiles and 9 boxes?
The same 120 square feet, 1/8 inch joint, and 10% waste produce an unrounded count of 64.98 because one tile covers 2.0314 square feet. Rounded up, that is 65 tiles. Boxes of 8 round 65 up to 9 boxes, with 7 spare. Without waste the count is 60 tiles and 8 boxes exactly. Type the number of tiles printed on your box. A box of 10 would not be 9 boxes.
How many 6 inch tiles cover an 8 by 10 foot floor?
With a 1/8 inch joint and 15% waste, the calculator shows 354 tiles, or 15 boxes of 24, with 6 spare. Coverage is 0.2605 square feet and the unrounded count is 353.13. Without waste the rounded count is 308 tiles and 13 boxes. Fifteen percent is what you type for a floor with a lot of cuts. A plain rectangle may not need it.
Can I use this tile count for paint or a concrete slab?
No. Paint is square feet of wall divided by coverage per gallon, on the room paint page. A 12 by 10 foot room there is a gallon question, not a tile question. Concrete is cubic feet from a thickness in inches, on the slab page. This form has no thickness and no gallon. It also does not convert metres. Convert the room to feet first, and type the tile’s inch size from the carton. The square footage page reports this 10 by 12 floor as 120.00 square feet, and 132.00 square feet after a 10% extra allowance. That 132 is the area this tile count divides by tile coverage. The square footage page does not return 130 tiles.
Related ClearCalc pages
- Square footage calculator This 10 by 12 floor is 120.00 square feet there, and 132.00 square feet after 10% extra. That page does not count tiles or grout joints.
- Room paint calculator Gallons from wall area. A 12 by 10 foot room there is not the 130 tiles this 10 by 12 floor needs.
- Concrete slab calculator Bags and cubic yards from a thickness. Tile is a count of pieces, not a volume.
- Length converter from meters Convert a metric room to feet before you type the length and width. Tile size stays in inches.
- Mulch calculator Cubic feet of a bed at a depth in inches. A different material and a different unit from a tile count.