Add each rectangle, subtract a real opening if there is one, and count tiles from the tile size and the grout joint. Waste starts at 10% and stays editable. Boxes round up from the tiles per box or from the coverage printed on the carton. You type the price. The math stays in your browser.
Measuring a kitchen backsplash
Measure each exposed run on its own. The usual place is the wall between the counter and the bottom of the upper cabinets. Do not assume that height is 18 inches. A tile backsplash that stops at the uppers on one wall and runs to the hood over the range is two different heights, so it is two rows in the calculator.
A return at the end of a cabinet, or the short side of a peninsula, is another row. If the fridge is a finished panel and you are not tiling behind it, leave that width out. If the tile stops at the fridge panel, end the tape there instead of running it into the fridge opening.
Outlets, switches, and a pot-filler pipe stay inside the area. You still buy the tile, then cut a hole in it. Subtracting a 2 inch by 4 inch box from a 15 sq ft splash changes the area by a few square inches and does not save a tile. What it does is ruin the tile you cut, which is why the waste field exists.
A window in the splash is different. If you are not tiling the glass, add the sash opening as an opening to subtract. You will still cut tiles around the frame, so do not also drop the waste to zero. A niche or a cabinet void larger than one tile is the same kind of subtraction. A switch plate is not.
Layouts, joints, and waste
The count uses a module: tile length plus one joint, times tile width plus one joint. A 3 inch by 6 inch tile with a 1/8 inch joint takes 3.125 by 6.125 inches, not 3 by 6. Leaving the joint blank counts the face only, which slightly overstates how many tiles fit. The joint is there so the count can be checked. It is not a grout recipe.
On a straight grid, the offcut from the end of one row often starts the next row, so a simple rectangle does not throw away every cut. Ten percent on that kind of layout is a common planning start. It is not pulled from a code book by this site. Change it when the layout stops working that way.
A diagonal turns the perimeter into triangles. A herringbone or a chevron cuts on a repeating angle, and many of those offcuts are too small to use. A large tile on a short backsplash has the same problem from the other direction: 10% of 15 sq ft is 1.5 sq ft, and one broken 12 inch tile is already about 1 sq ft. Look at the tile count, not only the percent. The calculator will not detect the pattern. You type the percent.
Daltile's pattern notes say to round tile footage up to the next whole foot. This page rounds a step further, to a whole tile and then a whole box, because that is how the material is sold. Their note is on Find the Right Tile Pattern. Installation methods, substrates, and joint requirements are the subject of the Tile Council of North America handbook, which this calculator does not apply.
Comparing cartons before you buy
Read the carton, not a memory of a similar tile. One box may say 15 tiles. Another may say it covers 15 sq ft. Fifteen 12 by 12 tiles are 15 sq ft of tile face, so those two figures can describe the same carton. A coverage that already includes the grout joint is larger than the faces.
A price per tile applies to the tiles you take home, not only the tiles the layout needs. Four boxes of 15 are 60 tiles even when the floor needs 45. If the carton gives a coverage and no tile count, this page will not invent a material total. Enter the tiles per box, or price the box. A price per box is the number of boxes times that price, and it does not need the tile count.
Plank and vinyl sold only by coverage, with no grout joint, belong on the flooring calculator instead.
Two hypothetical examples
The prices in both examples are made up so the arithmetic can be checked. They are not shelf prices, and they are not a quote.
A straight kitchen splash, where the tile count sets the boxes
Two runs, measured in feet. The tile is a 3 by 6 inch subway tile with a 1/8 inch joint, entered as 0.125. Waste stays at 10%. The carton is imagined to hold 40 tiles and to cost $28. No opening is subtracted.
- Behind the counter: 8 × 1.5 = 12 sq ft. The end return: 2 × 1.5 = 3 sq ft. Combined area = 15 sq ft.
- Tile face = 3 × 6 = 18 sq in. Module = (3 + 0.125) × (6 + 0.125) = 3.125 × 6.125 = 19.140625 sq in.
- 15 sq ft × 144 = 2,160 sq in. Tiles before waste = 2,160 ÷ 19.140625 = 112.849.
- Waste: 15 × 1.10 = 16.5 sq ft = 2,376 sq in. Tiles = 2,376 ÷ 19.140625 = 124.134, which rounds up to 125.
- Boxes = 125 ÷ 40 = 3.125, which rounds up to 4. Those boxes hold 160 tiles.
- Material, if you type $28 a box = 4 × 28 = $112. Optional costs left blank stay $0. The total of entered prices is $112.
The button “Try the backsplash example” fills these measurements and leaves the price blank. The $28 is only in this paragraph.
A bathroom floor, where four boxes cost more than the layout
One floor, 5 ft by 8 ft. The tile is 12 by 12 inches with a 1/4 inch joint, entered as 0.25. Waste is raised to 15% for a diagonal. The carton is imagined to hold 15 of those tiles, which is 15 sq ft of tile face, and the price used here is $4.50 a tile. Both the packing and the price are hypothetical.
- Floor area = 5 × 8 = 40 sq ft. Nothing is subtracted.
- Tile face = 12 × 12 = 144 sq in, which is 1 sq ft. Fifteen faces are 15 sq ft, so the carton figures agree.
- Module, with the joint = 12.25 × 12.25 = 150.0625 sq in. That is larger than the face, and it is not the 15 sq ft printed on the box.
- 40 × 144 = 5,760 sq in. Tiles before waste = 5,760 ÷ 150.0625 = 38.384.
- Waste: 40 × 1.15 = 46 sq ft = 6,624 sq in. Tiles = 6,624 ÷ 150.0625 = 44.142, which rounds up to 45.
- Boxes from the printed 15 sq ft = 46 ÷ 15 = 3.066…, which rounds up to 4. Four boxes contain 4 × 15 = 60 tiles.
- Material = 60 × $4.50 = $270. Charging 45 × $4.50 = $202.50 prices only the layout and leaves out 15 tiles that come home in those boxes.
If the carton says 15 sq ft and does not say 15 tiles, a price per tile is not turned into $270 or $202.50. Enter the tiles per box, or switch to a price per box.
Grout, adhesive, and the costs that stay at zero
This page will not tell you how many pounds of grout or how many bags of thinset to buy. The joint width is only part of it. Joint depth is usually the thickness of the tile, and a mosaic has far more joint than a 12 by 24. Adhesive coverage changes with the notch on the trowel and with whether the tile is back-buttered. Those numbers are printed on the product, and they move when the wall is out of flat.
MAPEI’s grout calculator says its coverage is for estimating and that job conditions and application change the amount. Use the product you are actually buying: MAPEI tile grouts calculator. If you already know what those bags will cost, open Optional costs and type the money. Blank lines stay at zero. They are not a hidden allowance.
Spacers, edge trim, a rented wet saw, and labour are the same kind of line. If a contractor has already given you one number for the whole job, do not rebuild their price out of these lines. Put your material total into DIY vs. hire and set it against the quote, with your hours.
Mistakes that change the order
- Measuring one long wall and forgetting the return beside the stove, or including the wall behind the fridge that you will not tile.
- Subtracting every outlet, then also adding 10% waste, and thinking both corrections were required for the same reason.
- Leaving the joint blank on a 1/8 inch installation, or typing 1/8 as 1.8 instead of 0.125.
- Using 10% for a herringbone because the field started there.
- Multiplying a price per tile by the layout count when the last box still contains spare tiles, or when the carton never said how many tiles are in it.
- Buying the exact tile count with no spare from the same lot. A later box can be a different shade. The waste field is the place to keep that spare. This page does not add a second spare on its own.
- Treating the result as a statement that the wall is flat enough, or that the job needs no waterproofing. It is neither.
Assumptions
Areas are rectangles
Each section is length × width. Openings you add are subtracted once. An outlet or a pipe is not an opening unless you add it. A blank opening row is ignored.
One joint is added to each side
The space one tile takes is (tile length + joint) × (tile width + joint). A blank joint means zero, so the count uses the tile face only. The joint does not estimate grout by the bag.
Waste is added once, then tiles round up
Ten percent multiplies the net area by 1.10 before the tile count. The count then rounds up to a whole tile. Typing 0 means no extra area. The job type does not change that percent.
Boxes use one carton figure
Count boxes from the tiles per box, or from the area printed on the carton, not both. The other figure is ignored. Boxes round up. An exact fit does not add a box.
One tile price
Price by the box or by the tile, not both. A blank material price is shown as “Price not entered” and is not treated as free. A price per tile is charged on every tile in the boxes you buy, including spare tiles in the last box. Printed coverage alone cannot make that count. Enter the tiles per box, or use a price per box.
Optional costs start at zero
Adhesive, grout, spacers, trim, tools, labour, and miscellaneous expenses are zero until you type a number. This page does not turn the joint into pounds of grout or bags of adhesive.
Questions
How is the tile count calculated?
Each area is length times width. Openings you add are subtracted. One tile occupies its face plus one grout joint on the length and one on the width. The net area divided by that module is the count before waste. Waste multiplies the net area, and the result rounds up to a whole tile.
Why does the waste field start at 10 percent?
Ten percent is a planning start for a straight layout on a simple rectangle, not a rule for every job. A diagonal or a herringbone cuts triangles that are hard to reuse, so people commonly type 15 or more. The job type does not change the number. Type the allowance you actually want, including 0.
Should I subtract outlets and pipe holes?
No. An outlet cover is a small hole in a tile you still have to buy. Subtract a window, a door, or another opening that is larger than a tile and that you are not tiling. The notes below walk through a kitchen splash.
Tiles per box or square feet per box?
Use one figure to count the boxes. Tiles per box rounds the tile total up to whole cartons. Coverage per box divides the area after waste by the figure printed on the carton. A price per tile is then charged on every tile in the boxes you buy, which includes spare tiles in the last box. If you only have a coverage and a price per tile, enter the tiles per box or switch to a price per box. No exact material cost is shown until you do.
Does this estimate grout or thinset bags?
No. A bag's coverage depends on the product, the joint width, the joint depth, and the trowel. MAPEI's own grout calculator says its figures are estimates and that job conditions change them. Type what you expect to pay for adhesive, grout, spacers, and trim, or leave those lines at zero.
Can I use the total in the DIY comparison?
Yes. Put the total you got here into the materials line of the DIY vs. hire calculator, then add your hours and the quote. Do not add the box price a second time. This page does not decide whether you should install the tile.