Tile Calculator

Tiles = ⌈(Floor area / Tile area) × (1 + Waste%)⌉

Construction

How to Use This Tool

Tile calculator

Enter the dimensions of your floor, wall, or backsplash along with the tile size to find out how many tiles you need. This calculator includes a waste factor so you buy enough to cover cuts, breakage, and pattern matching. Below you will find common tile sizes, layout patterns, and tips for estimating materials accurately.

Common tile sizes

Tile size (inches) Tile size (cm) Tiles per sq ft Typical use
1 x 1 2.5 x 2.5 144 Mosaic sheets, shower floors
2 x 2 5 x 5 36 Mosaic sheets, accents
4 x 4 10 x 10 9 Backsplashes, small walls
6 x 6 15 x 15 4 Backsplashes, countertops
3 x 6 (subway) 7.5 x 15 8 Backsplashes, bathroom walls
12 x 12 30 x 30 1 Floors, walls
12 x 24 30 x 60 0.5 Floors, large walls
18 x 18 45 x 45 0.44 Floors
24 x 24 60 x 60 0.25 Large floors

The “tiles per square foot” column assumes no grout lines. In practice, grout joints (typically 1/16 to 1/4 inch wide) reduce the number of tiles slightly, but the difference is small enough that most calculators ignore it and compensate through the waste factor.

How to calculate tiles needed

Step 1: Measure the area

For a floor, multiply the room length by the width. A room that measures 10 feet by 12 feet has 120 square feet of floor space. For a wall, multiply the width by the height. A backsplash that runs 8 feet wide and 18 inches (1.5 feet) tall covers 12 square feet.

Step 2: Calculate tile area

Convert the tile dimensions to feet (divide inches by 12), then multiply length by width. A 12 x 12 inch tile is 1 x 1 foot = 1 square foot per tile. A 6 x 6 inch tile is 0.5 x 0.5 = 0.25 square feet per tile.

Step 3: Divide and add waste

Divide the total area by the area per tile. Then add 10 percent for waste on a straight layout, or 15 percent for a diagonal or herringbone layout. The 120 sq ft room with 12 x 12 inch tiles needs 120 tiles plus 10 percent waste = 132 tiles. Round up to the nearest full box.

Worked example with smaller tiles

A bathroom floor measures 5 x 8 feet (40 sq ft). Using 6 x 6 inch tiles (0.25 sq ft each): 40 / 0.25 = 160 tiles. Add 10 percent: 160 x 1.10 = 176 tiles. If tiles come in boxes of 11, you need 16 boxes.

How much waste to plan for

Layout pattern Recommended waste Why
Straight (grid) 10% Minimal cuts at edges
Brick/offset 10 to 12% Staggered rows need half-tiles at ends
Diagonal (45 degrees) 15% Angled cuts along all edges
Herringbone 15 to 20% Many angled cuts, more breakage
Chevron 15 to 20% Similar to herringbone
Complex mosaic 20% Irregular cuts, pattern matching

These percentages cover cuts, breakage during installation, and a few spares for future repairs. If you are working with natural stone tiles, which break more easily than porcelain, add an extra 5 percent.

Layout patterns explained

A straight grid is the simplest pattern. Tiles line up in rows and columns with all grout lines running continuously. It uses the least material and works with any tile shape.

A brick or offset pattern staggers each row by half the tile width, like brickwork. It works well with subway tiles and rectangular floor tiles. The offset hides slight size variations between tiles.

Diagonal layout rotates the grid 45 degrees. It makes small rooms feel larger but requires angled cuts along every wall edge, which means more waste and more labor time.

Herringbone arranges rectangular tiles in a zigzag pattern where each tile meets the next at a right angle. It looks striking on floors and backsplashes but takes the most skill to install and wastes the most material at the edges.

Estimating grout and mortar

Thin-set mortar (the adhesive under the tiles) covers about 60 to 80 square feet per 50-pound bag when applied with a 1/4 x 1/4 inch square-notch trowel. Larger tiles need a larger trowel (1/2 x 1/2 inch), which uses more mortar per square foot.

Grout coverage depends on tile size, grout joint width, and tile thickness. As a rough guide, a 25-pound bag of sanded grout covers about 100 to 200 square feet of 12 x 12 inch tile with 1/8 inch joints. Smaller tiles with wider joints use grout faster. The grout bag label usually has a coverage chart for common tile sizes.

Tips for ordering tiles

  • Buy all your tiles from the same production lot. Colors can shift slightly between batches. The lot number is printed on the box. Check every box at the store and request matching lots.
  • Keep 2 to 3 spare tiles after installation for future repairs. Tile lines get discontinued, and matching a replacement years later can be difficult.
  • Measure twice. A mistake in your room dimensions throws off the entire order. Double-check by measuring from opposite corners and comparing the diagonals.
  • If the room has alcoves, closets, or irregular shapes, break it into rectangles. Calculate each rectangle separately, then add the areas together before dividing by tile size.

Frequently asked questions

How many 12×12 tiles do I need for 100 square feet?

100 tiles plus waste. With 10 percent waste for a straight layout, buy 110 tiles.

How do I convert tile sizes from inches to centimeters?

Multiply inches by 2.54. A 12-inch tile is 30.48 cm. Tile manufacturers often round to the nearest whole centimeter, so a “30 x 30 cm” tile and a “12 x 12 inch” tile are the same product.

Should I include the grout line in my calculation?

For most projects, no. The grout joint reduces the number of tiles slightly, but the waste factor more than compensates. Professional estimators typically ignore grout lines and rely on the waste percentage.

How many boxes of tile should I buy?

Check the box label for the square footage per box. Divide your total area (with waste added) by the coverage per box and round up. A 100 sq ft project with 10 percent waste needs 110 sq ft of tile. If each box covers 11 sq ft, buy 10 boxes.

Can I return unused tiles?

Most stores accept returns of unopened boxes within 30 to 90 days with a receipt. Opened boxes and cut tiles usually cannot be returned. Check the store policy before buying.

What is the cheapest tile layout?

A straight grid with 12 x 12 or 12 x 24 inch tiles wastes the least material, requires the fewest cuts, and installs fastest. Smaller tiles and complex patterns cost more in both materials and labor.

Measurement guides

Formula & Explanation

We round up to the nearest whole tile because you can't buy partial tiles. The waste percentage covers cuts, breakage, and future repairs.