Tile Calculator

How it works

Every tile covers a small piece of floor: its own size plus a share of the grout joint around it. The number of tiles is the area to cover divided by that, plus an allowance for waste, rounded up:

tiles = (area × (1 + waste %)) / ((tile length + joint) × (tile width + joint))

You enter the length and width of the floor or wall, the size of one tile, and optionally the grout joint, a waste allowance and the number of tiles in a box. Left empty, the joint is 0 and the waste is 10 percent. If you give the tiles per box, the calculator also returns the boxes to buy and the tiles they contain. Use metric (meters, centimeters, millimeters) or imperial (feet, inches); the units follow your region and can be switched at the top.

The count is calculated with exact whole-number arithmetic after converting every length to a tenth of a millimeter. That matters at the boundary: a floor that divides into tiles exactly, like 6 m² of 50 × 50 cm tiles, gives exactly 24, not 25, which a floating-point calculation can get wrong by a hair.

This is an area-based estimate. It does not draw your layout, so it cannot know exactly where each cut falls. That is what the waste allowance is for.

The joint is part of each tile's footprint

The joint is added once to each side of the tile, so a 30 × 30 cm tile with a 3 mm joint occupies a 303 × 303 mm cell. The smaller the tile, the bigger the share the joint takes. On a 12 m² floor, a 30 × 30 cm tile drops from 134 to 131 pieces with a 3 mm joint, while a 10 × 10 cm tile drops from 1,200 to 1,132.

Watch the units. In the metric version the floor is in meters, the tile in centimeters and the joint in millimeters. In the imperial version the floor is in feet, and both the tile and the joint are in inches, so a 1/8 inch joint is typed as 0.125. The calculator accepts joints up to 50 mm.

Floor or wall

A wall works the same way: enter its width and height where the floor's length and width would go. The one thing the calculator does not have is a field for windows, niches or a bath panel. For a wall with a large opening, split the wall into rectangles around it, calculate each one and add the counts. Each part is rounded up separately, so the total comes out a little generous, which is usually welcome around an opening where extra cuts are needed.

From the box label to tiles per box

Labels give either the number of tiles or the area a box covers. The calculator asks for tiles per box, so divide the area on the box by the area of one tile. The label area is normally the faces of the tiles themselves, without joints, but ask the seller if it is not clear.

Examples

A floor. A 4 × 3 m floor is 12 m². With 30 × 30 cm tiles you need 12 / 0.09 = 133.3, so 134 tiles. With 10 percent waste, 147 tiles.

Boxes. If a box holds 10 tiles, 147 tiles means 15 boxes, 150 tiles, so 3 spares.

With grout. The same floor with a 3 mm joint needs 131 tiles, or 144 with 10 percent waste.

A different tile. With 60 × 30 cm tiles (0.18 m² each), the 12 m² floor takes 67 tiles, or 74 with 10 percent waste. Bigger tiles mean fewer pieces, but each cut wastes more.

In feet and inches. A 12 × 10 ft floor is 120 ft². With 12 × 12 in tiles (1 ft² each) it takes 120 tiles, or 132 with 10 percent waste.

The same floor with an inch joint. With a 1/8 inch joint each cell is 12.125 × 12.125 in = 147.015625 in². The floor is 120 × 144 = 17,280 in², so 17,280 / 147.015625 = 117.5, which is 118 tiles before waste.

A small tile. On the 12 m² floor, 10 × 10 cm tiles (0.01 m² each) need 12 / 0.01 = 1,200 with no joint. With a 3 mm joint a cell is 103 × 103 mm = 10,609 mm², and 12,000,000 / 10,609 = 1,131.1, so 1,132 tiles.

A wall. A wall 3.6 m wide and 2.4 m high is 3.6 × 2.4 = 8.64 m². Tiles of 30 × 60 cm (0.18 m²) need 8.64 / 0.18 = exactly 48. With 10 percent waste: 8.64 × 1.1 = 9.504, and 9.504 / 0.18 = 52.8, so 53 tiles.

Tiles per box from the label. The 12 m² floor with 60 × 60 cm tiles needs 12 × 1.1 / 0.36 = 36.7, so 37 tiles with 10 percent waste. A box of 1.44 m² holds 4 tiles, so 37 / 4 = 9.25 and you buy 10 boxes: 40 tiles, 14.4 m², with 3 tiles to spare.

Things to watch for

Waste and layout

The waste field is where the layout goes, because the calculator has no pattern selector. In a straight grid the cuts happen only along the last row and column, and the piece cut off one end can often finish the other end of the row. A diagonal layout cuts every tile along the edges at an angle, and those triangular offcuts rarely fit anywhere else. Herringbone has a similar problem along every edge. Rooms with many corners, pipes or fixtures, and large tiles, also produce more offcuts. Raise the allowance for these. The 5, 10 and 15 percent figures in the questions below are rules of thumb, not measurements of your room, and a tiler who has seen the plan can tell you more.

Whole boxes help here: whatever you buy beyond your count is your stock of spares, so the box rounding is rarely wasted.

Before you order

• Measure the area you will actually tile. Subtract fixed items such as a bath panel only if you will not tile under them. When in doubt, include them.
• Order everything from one batch. Shade and size can differ between batches. Check the batch numbers and keep spare tiles.
• Use the real tile size. Nominal sizes are often rounded. Use the measured size of the tile, and the joint your tiler will use, which is commonly 2 to 3 mm for rectified floor tiles and wider for others.
• Adhesive and grout are separate. This calculator counts tiles. How much adhesive and grout you need depends on the tile, the joint and the surface.
• Everything runs in your browser. The measurements you enter are not sent to a server.

For the floor or wall area on its own, use the area calculator, and for painting the room, the paint calculator.