Tile Calculator

How to measure for tile

For floors, measure the length and width of the room in feet and multiply. For walls, such as a shower surround or backsplash, multiply the width of each wall by the height you will tile and add them up. Subtract only large openings like windows or a tub. Small outlets and switch plates are not worth subtracting. The square footage calculator handles L-shaped rooms.

Then look up the tile size. Use the nominal size on the box (for example 12 × 24 in). The calculator uses that face size to figure how many tiles cover a square foot.

The formula

Coverage per tile = length × width ÷ 144 sq ft. Tiles = area ÷ coverage per tile, plus waste, rounded up. If you enter tiles per box, the calculator also rounds up to whole boxes.

Worked example

A 60 sq ft bathroom floor using 12 × 24 in tiles, 8 tiles per box, with 10% waste:

• Each tile: 12 × 24 ÷ 144 = 2 sq ft
• 60 ÷ 2 = 30 tiles
• Add 10%: 33 tiles
• 33 ÷ 8 = 4.1, so 5 boxes

Most stores do not split boxes, so the extra tiles from the fifth box become your spares.

Waste factors

• Straight layouts with standard-size tile: about 10%
• Diagonal layouts, herringbone or large-format tiles: about 15% or more
• Small rooms with many corners and cuts: lean higher, since a bigger share of tiles gets cut

Natural stone and handmade tiles vary piece to piece, and some pieces get rejected for color or chips, so add extra there too.

Common mistakes

• Buying exactly enough. Breakage and miscuts happen. Keep a few spare tiles for future repairs; matching a discontinued tile later can be impossible.
• Mixing lots. Check that every box has the same lot or shade number printed on it. Color can vary between production runs.
• Not dry-laying. Lay out a row before setting to center the pattern and avoid thin slivers at walls and doorways.
• Using the wrong trowel. Notch size depends on the tile size and the thinset maker's instructions. Large tiles usually need bigger notches.
• Skipping a flat substrate. Large-format tiles need a very flat floor, or they lip and crack.

Buying tips

• Tile is sold by the piece or by the box, and each box label lists the square feet it covers and the piece count. Enter the piece count in the calculator for an exact box number.
• Thinset mortar and grout are sold in bags. Each bag lists approximate coverage by tile size, trowel notch and joint width. Check the chart on the bag.
• Plan trim pieces (bullnose, edge trim or Schluter-style profiles) for exposed edges. They are often sold by the piece or linear foot.
• Many stores accept returns of full, unopened boxes. Ask about the policy before buying extra.