Tile Calculator
Enter the size of your floor or wall, the size of one tile and the grout joint to see how many tiles and boxes to buy. A waste allowance covers cuts and breakage.
How to use this tile calculator
- Measure the length and width of the floor or wall. Subtract large gaps by splitting the room into sections.
- Enter the length and width of one tile in inches, using the nominal size on the box.
- Enter the grout joint width. Use 0 if you only want the area-based count.
- Keep or change the waste allowance. A straight layout in a plain room needs less than a diagonal or patterned one.
- Enter the tiles per box and, if you like, a price per tile. Press Calculate, then use Copy result or Export CSV.
How to calculate how many tiles you need
The calculator divides the area by the area of one tile plus its share of the grout joint, then adds waste.
- Area = length (ft) x width (ft)
- Area per tile = (tile length + joint) x (tile width + joint) / 144 square feet, with sizes in inches
- Tiles = area x (1 + waste % / 100) / area per tile, rounded up
- Boxes = tiles / tiles per box, rounded up
- Cost = tiles x price per tile
Worked example
You are tiling a floor that is 10 ft by 8 ft, so the area is 80 sq ft. The tiles are 12 in by 12 in and the joint is set to 0 for a clean count. Each tile covers 1 sq ft. With 10% waste you need 80 x 1.10 = 88 sq ft, so 88 tiles. A box holds 10 tiles, so you need 8.8, which rounds up to 9 boxes.
With a 0.125 inch joint, each tile takes up 1.021 sq ft, so the same job needs 87 tiles, still 9 boxes.
Assumptions & limits
- The area is a rectangle with no cut-outs. Subtract large fixtures by treating the room as sections.
- Tile sizes on the box are often nominal, so measure a real tile if the fit matters.
- The waste allowance is not a standard. It depends on layout, tile size, skill and how much breakage you expect.
- The price per tile is your own input. The calculator does not look up prices, and it excludes grout, mortar, backer board and labor.
- Buy a little extra from the same batch, because color and size can differ between production runs.
Frequently asked questions
How do I calculate how many tiles I need?
Divide the area by the area of one tile, then add waste. A 10 ft by 8 ft floor is 80 sq ft, and with 12 in by 12 in tiles and 10 percent waste you need 88 tiles.
How much waste should I allow for tile?
Ten percent is a common starting point for a straight layout. Diagonal patterns, large tiles and rooms with many corners need more.
How do I find the area of one tile?
Multiply the length by the width in inches and divide by 144. A 12 in by 24 in tile is 288 sq in, which is 2 sq ft.
Does the grout joint change the count?
Slightly. Each tile takes up its own area plus half a joint on each side. The default is 0.125 inch, and you can enter 0 to ignore it.
How many boxes of tile do I need?
Divide the tile count by the tiles in a box and round up. Many boxes list the square feet they cover instead, so check the label.
Can I use this for a wall or backsplash?
Yes. Enter the wall height and width as the length and width, and subtract windows and outlets by treating them as separate sections.
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Last updated: November 2026