1. Pick Imperial or Metric. Enter the length and width of the floor or wall, and any area to leave out, such as a vanity or window.
2. Enter the tile size and the grout joint. Use the actual tile size printed on the box.
3. Set your waste allowance, the tiles per box and your price per box. Read the tiles to buy, the boxes and the cost.

A tile calculator is a counting tool for ceramic, porcelain and stone tile. It divides the surface you want to cover by the space one tile takes, then turns that count into whole boxes, since tile is sold by the box.

It helps homeowners pricing a bathroom floor or kitchen backsplash, and installers checking an order before it ships. Knowing the box count early also lets you buy every box from the same production lot.

It does not plan the layout or count grout bags. For grout, use the grout calculator, which uses the joint width and tile thickness.

The calculator treats each tile as its own size plus one grout joint, divides the area by that space, then adds waste and rounds up.

1. Area. Length x width, minus any area left out, converted to square inches (x 144) or square centimeters (x 10,000).
2. Tile module. Add one joint to each tile dimension. A 12 inch tile with a 1/8 inch joint takes up 12.125 x 12.125 = 147.02 square inches.
3. Exact count. Area divided by the module.
4. Waste and boxes. Multiply by 1 plus your waste allowance, round up to a whole tile, then divide by tiles per box and round up again.

Including the joint makes the count slightly smaller than area divided by tile size alone. On the 10 x 8 ft example, it drops the exact count from 80.0 to 78.4 tiles.

Bathroom floor. A 10 ft x 8 ft floor is 80 sq ft, or 11,520 sq in. With 12 in tiles and 1/8 in joints, each tile takes 147.02 sq in, so the exact count is 78.36. At 10 percent waste that is 86.2, rounded up to 87 tiles. With 10 tiles per box you buy 9 boxes and keep 3 spares. At $25 a box, the tile costs $225.00.

Large-format floor. A 15 ft x 12 ft room is 180 sq ft. With 24 in tiles and 1/8 in joints, the exact count is 44.53. At 15 percent waste you need 52 tiles, which is 18 boxes of 3. At $60 a box, that is $1,080.00.

Diagonal layout. A 12 ft x 12 ft floor in 12 x 24 in tile laid on a diagonal gives an exact count of 70.89. With a 15 percent allowance for the extra cuts, you need 82 tiles, or 11 boxes of 8.

Metric backsplash. A 3 m x 0.6 m wall is 1.8 sq m. With 15 x 10 cm tiles and 2 mm joints, the exact count is 116.1. At 10 percent waste you need 128 tiles, or 7 boxes of 20.

The layout and the size of the tile change the waste far more than the area does.

Layout Pattern

A straight grid cuts only the edge tiles. Diagonal, herringbone and chevron layouts cut tiles along every wall, so they need a bigger allowance. The waste field is yours to set, since no standard fixes one figure.

Tile Size Versus Room Size

Large tiles in a small room leave more of each tile as offcuts. A 24 inch tile in a 5 foot wide bathroom wastes a large piece at one wall.

Grout Joint Width

Wider joints spread tiles further apart and lower the count slightly. ANSI A108.02 sets a 1/16 inch minimum and says the joint should be at least three times the size variation of the tile.

Tile Variation

The Tile Council of North America notes some tiles ship with about 3/32 inch between the largest and smallest in a box. That variation, not taste alone, sets how narrow your joint can be.

Openings and Fixtures

Leave out areas under cabinets or a tub only if you will not tile there. Many installers tile under freestanding vanities, so check first.

Tile cost is boxes times your box price, and the tile is only one part of a tiling budget.

Keep spare tiles from the same lot for repairs. Replacement boxes from a later run can differ in shade and size.

Bathroom and Kitchen Floors

Measure wall to wall, leave out fixed cabinets, and enter the actual tile size. The flooring and tile quantities guide covers rooms with more than one rectangle.

Backsplashes and Shower Walls

Use the wall height as the width, and leave out windows and niches. Small tiles on mesh sheets are counted by sheet, so enter the sheet size as the tile size and a joint of 0.

Comparing Tile Sizes

Run the same room with two tile sizes to compare box counts and cost. For a seamless coated garage floor instead of tile, see the polyurea calculator.

1. Using Nominal Size

A tile sold as 12 x 24 may measure a little less. Enter the actual size printed on the box.

2. Skipping the Waste Allowance

An exact count assumes every cut piece is reused. Real cuts leave offcuts, so an order with no allowance runs short. The material waste guide explains how allowances work.

3. Rounding Boxes Down

Stores sell whole boxes. 8.7 boxes means 9.

4. Buying from Different Lots

Boxes from different production runs can differ in shade. Buy the full order at once and check the lot numbers.

5. Mixing Units

A room in feet and a tile in inches must be converted before dividing. The calculator converts both for you.

The count is exact for a rectangle with the joint included. The waste allowance is your judgement, so the final order is an estimate.

You need 100 tiles with no joint, or about 98 with 1/8 inch joints, before waste. At 10 percent waste, order 108 tiles.

There is no standard figure. Straight layouts cut fewer tiles than diagonal or herringbone ones, so set a larger allowance for patterned floors and small rooms.

Yes, slightly. Each tile takes its own size plus one joint, so wider joints mean a few fewer tiles. The effect is bigger with small tiles.

ANSI A108.02 says a grout joint should never be less than 1/16 inch. It also asks for at least three times the size variation of the tile.

For tiles with any side over 15 inches, ANSI A108.02 calls for at least 1/8 inch on rectified tile and an average of 3/16 inch on calibrated tile.

Split it into two rectangles, run each one, and add the tile counts. Apply the waste allowance to the total.

Only if you will not tile there. Fixed kitchen cabinets are often left untiled, while freestanding furniture usually sits on tile.

Keep the spares from the last box for future repairs. Tile from a later production run may not match in shade or size.

Yes. Enter the sheet size as the tile size and a joint of 0, then read the count as sheets.

No. The calculation runs in your browser and nothing is sent to our servers. Anything you choose to Save stays in this browser only.

• Grout joint width in ANSI A108.02: three times the tile variation and 1/16 inch minimum (Ceramic Tile Foundation).
• Grout FAQ: joint width, tile size variation and sanded vs unsanded grout (Tile Council of North America).
• Exact conversion factors for the inch, foot and square foot (NIST SP 811, Appendix B.8).