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Tile Calculator
Our free tile calculator tells you how many tiles you need for a floor or a wall, with a waste allowance for cuts and breakage. Enter the room size, the tile size, and how many tiles come in a box, and it works out the tiles needed, the total to buy, and the number of boxes.
10% for a straight lay; 15% for diagonal patterns.
Estimates only — check the store price per tile or per box.
| Room area | |
| Tiles needed (no waste) | |
| Waste tiles | |
| Boxes to buy | |
| Estimated cost |
How it works
Tiling a room starts with two areas: the area of the floor and the area of one tile. Divide the floor area by the tile area and you get the number of tiles that would cover the room perfectly, with no cuts and no mistakes. Real rooms are never perfect, so the calculator then adds a waste allowance, usually 10 percent, for the tiles you cut around doorways and edges, plus any that chip during the job.
Measure the room length and width in feet, in the longest and widest spots. If the room is L-shaped, split it into two rectangles, work out each area, and add them together. Enter the tile size in inches, exactly as printed on the box: a 12 by 12 inch tile, a 12 by 24 inch plank tile, or a small 4 by 4 inch wall tile all work the same way. Enter how many tiles come in a box, because stores sell by the box and you cannot buy half a box.
One tile (sq ft) = Tile length (in) × Tile width (in) ÷ 144
Tiles needed = Room area ÷ One tile area
Tiles to buy = Tiles needed × (1 + Waste % ÷ 100), rounded up
Boxes = Tiles to buy ÷ Tiles per box, rounded up
There are 144 square inches in a square foot, which is why the tile area is divided by 144. A 12 by 12 inch tile is exactly 1 square foot, so the math is easy with that size. A 12 by 24 inch tile is 2 square feet, so a 120 square foot room needs only 60 of them before waste. The calculator always rounds the final tile count up to a whole tile, and the box count up to a whole box, because you cannot buy part of a tile or part of a box.
The grout gap between tiles is usually 1/8 to 1/4 inch. It is small enough to ignore in the count, and the waste allowance more than covers it. The same method works for a wall: measure the wall length and height in feet instead of length and width, and subtract the area of any window or large opening first.
Worked example
Say you are retiling a bathroom floor in Florida. The room is 10 feet long and 12 feet wide, and you picked 12 by 12 inch ceramic tiles that come 10 to a box. Here is the math, step by step.
First, the room area: 10 × 12 = 120 square feet. Next, the area of one tile: 12 × 12 = 144 square inches, and 144 ÷ 144 = 1 square foot per tile. Divide the room by the tile: 120 ÷ 1 = 120 tiles with no waste. Add the 10 percent waste allowance: 120 × 10% = 12 extra tiles, so 120 + 12 = 132 tiles to buy. Finally, the boxes: 132 ÷ 10 = 13.2, rounded up to 14 boxes. At $2 per tile, the tiles cost about $264, plus grout, adhesive, and spacers.
Now suppose you choose larger 12 by 24 inch tiles instead. Each tile covers 2 square feet, so the room needs 120 ÷ 2 = 60 tiles, plus 10 percent waste, which is 6 more, for 66 tiles total. Fewer, bigger tiles mean fewer grout lines and a faster install, which is one reason large-format tiles are popular in US kitchens and living rooms.
FAQ
How many tiles do I need for a 10x12 room?
A 10 by 12 foot room is 120 square feet. With 12 by 12 inch tiles, each covering 1 square foot, you need 120 tiles, plus 10 percent waste, which is 12 more, for a total of 132 tiles. If tiles come 10 to a box, buy 14 boxes.
How much extra tile should I buy for waste?
Buy 10 percent extra for a simple straight-lay floor, and 15 percent for a diagonal pattern or a room with many corners, doorways, and cuts. The extra covers cut pieces, chipped tiles, and spares for future repairs.
How do I calculate tiles for a wall?
Measure the wall length and height in feet, multiply them for the square footage, and divide by the area of one tile. Subtract the area of any large opening, such as a window, then add your waste percentage. The calculator above works the same way for walls.
What is the grout gap, and does it change the count?
The grout gap is the small space between tiles, usually 1/8 to 1/4 inch, filled with grout. For planning, it is small enough to ignore in the tile count, and the waste allowance covers it. Tilers set the gap with spacers as they work.
Should I buy tiles by the box or by the piece?
Most US stores sell tile by the box, and boxes cannot be split, so round up to whole boxes. This calculator does that for you when you enter the number of tiles per box. Keep one spare box if you can, in case a tile cracks later.