Tile Calculator — How Many Tiles and Boxes to Buy

How to use the tile calculator

Keep Imperial (ft) selected and enter the length and width of the area. For a wall or backsplash, enter its width and height.
Enter the tile's nominal size in inches, for example 12 × 24.
Set the waste allowance: 10% for a straight layout, 15% or more for diagonal, herringbone or large-format tile.
Enter the square feet per box printed on the carton to get the box count. Leave it at 0 if you buy loose tiles.
Open Advanced options to change the grout joint (default 1/8 in, entered as 0.125).

For an L-shaped room, split it into rectangles, run each one and add the results.

How the calculator works

Area = length × width
Area with waste = area × (1 + waste %)
Space per tile = (tile length + joint) × (tile width + joint)
Tiles = area with waste ÷ space per tile, rounded up
Boxes = area with waste ÷ square feet per box, rounded up

Including the grout joint is slightly more accurate than dividing by the bare tile area, because each tile plus its share of the joint covers a bit more floor. On large tiles the difference is small; on mosaics and small tiles with wide joints it adds up.

Choosing a grout joint

The Tile Council of North America (TCNA) notes there is no single standard size for a grout joint. ANSI A108.02 asks for straight, even joints, and TCNA explains that a joint narrower than about three times the tile-to-tile size variation tends to look irregular. Follow the manufacturer's recommended joint for your tile. TCNA also suggests unsanded grout for joints under 1/8 in and sanded grout for 1/8 in and wider.

Worked examples

Kitchen floor, 12 × 10 ft, 12 × 24 in tile

1/8 in grout joint, 10% waste, 15.5 sq ft per box. The floor is 120 sq ft, or 132 sq ft with waste. You need 65 tiles and 9 boxes.

Same floor laid diagonally, 18 × 18 in tile

With 15% waste the order area becomes 138 sq ft. That is 61 tiles, and with 13.5 sq ft per box, 11 boxes.

Backsplash, 10 ft × 1.5 ft, 3 × 6 in subway tile

1/16 in joint and 10% waste on 15 sq ft: 128 tiles. Small tiles add up fast, so check how many pieces or sheets come in a carton before you order.

Before you order

The box count is based on area, so compare it with the tile count and the number of pieces per carton printed on the box. Buy all boxes at once: Clé Tile points out that tiles from the same production run match in shade and finish, while a later batch may look slightly different. Keep a box or two after the job for repairs, since styles and colors get discontinued.

The calculator covers field tile only. Bullnose, trim pieces, thinset, grout and backer board are ordered separately.

Frequently asked questions

How much extra tile should I buy?

Plan on 10% for a simple straight layout. Diagonal and herringbone patterns produce more cuts, so 15% is safer, and rooms with many corners or obstacles can need more.

How many 12 × 24 tiles do I need for 100 sq ft?

Each 12 × 24 tile covers 2 sq ft before grout. For 10 × 10 ft with a 1/8 in joint and 10% waste, the calculator gives 55 tiles, or 8 boxes at 15.5 sq ft per box.

Does the grout joint change the number of tiles?

A little. In the 12 × 10 ft kitchen, a 1/8 in joint brings the count from 66 to 65 tiles. With small tiles and wide joints the effect is larger.

Can I use this for walls and showers?

Yes. Enter each wall's width and height as length and width, run the calculator for each wall and add the results. Subtract windows and niches if they are large.

Why do I need more waste with large-format tile?

Large tiles need fewer cuts, but each offcut is a big piece of material that often can't be reused elsewhere. A single broken tile also costs more.

Sources

This is a material estimate for rectangular areas. Confirm measurements on site and follow the tile manufacturer's instructions for joint width and installation.

Results