Calculators

Tile Calculator

How many tiles and boxes for a floor or wall, allowing for the grout joint and waste for your layout.

How it works

Each tile covers its own size plus half the grout joint on every side, which is the same as the tile plus one joint in each direction. Divide the area in square inches by that footprint to get the tiles laid edge to edge, then add waste for cuts and breakage: about 10% for a straight lay, 15% for an offset and 20% for diagonal or herringbone patterns.

tiles = area × 144 ÷ ((w + g) × (l + g)) × (1 + waste)
w, l
Tile width and length, in inches
g
Grout joint width, in inches
144
Square inches in a square foot

Worked example

A 12 × 10 ft floor in 12 × 24 in tiles with 1/8 in grout, straight lay, 8 tiles to a box.

  1. 1Area: 12 × 10 = 120 sq ft
  2. 2Each tile covers 12.125 × 24.125 ÷ 144 = 2.03 sq ft
  3. 3Tiles: 120 ÷ 2.03 = 59.1
  4. 4With 10% waste: 65 tiles
  5. 5Boxes: 65 ÷ 8 = 8.1, so 9 boxes

Buy 9 boxes (72 tiles), leaving 7 spare for repairs. At $38 a box that is $342.

Frequently asked questions

How much extra tile should I buy?

10% for a straight grid in a simple room, 15% for brick or offset patterns and rooms with many corners, and 20% for diagonal and herringbone layouts, which cut a tile at every edge. Large-format tiles break more expensively, so lean to the higher figure.

Does grout width change how many tiles I need?

Slightly. A wider joint means each tile covers a little more area, so you need fewer tiles. With small tiles such as mosaics the effect is larger: a 1/8 in joint on a 2 in tile adds about 13% to each tile's coverage.

How do I tile an L-shaped room?

Split it into rectangles, work out each area, and add them together. Enter the total as a single rectangle, such as its square footage × 1 ft, or run the calculator for each part and add the tiles before rounding up to boxes.

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