Tile Calculator

The formula

Coverage and yield assumptions

Tile sizes are often nominal: a "12 × 12" may measure 11-7/8 in. Use the actual size from the spec sheet. Joint width defaults to 1/8 in; the TCNA Handbook and ANSI A108 set a minimum of 1/16 in, and rectified porcelain is often set at 1/16–1/8 in while handmade or calibrated tile may need 3/16 in or more.

Floor vs wall tile

For walls, measure each surface as height × width and subtract windows, mirrors and cabinets that will not be tiled. Tub surrounds are usually three walls to about 6 ft above the tub. Backsplashes run from countertop to the bottom of the upper cabinets, often 18 in. Floors include the area under freestanding appliances but not under cabinets.

Large-format tile

Tiles with any edge 15 in or longer are classed as large format. They need a flatter substrate (often no more than 1/8 in variation over 10 ft), large-and-heavy-tile mortar and offset limits of 33% or less to avoid lippage from bowed tile. They also waste more at the edges of a room because each cut removes a bigger piece.

Planning the layout

Dry-lay a row along both axes before setting. Start from the center of the room or a visible focal line so cuts at opposite walls are equal and wider than half a tile. Patterns like herringbone, diagonal or versailles need more cuts and more waste. Mix tiles from several boxes as you go so shade variation blends.

Other materials to buy

• Thinset mortar: a 50 lb bag covers roughly 40–95 sq ft depending on trowel size.
• Grout: estimate it with our grout calculator.
• Backer board or an uncoupling membrane for floors and wet areas.
• Spacers, leveling clips and a waterproofing membrane for showers.

Common mistakes to avoid

• Using the nominal tile size when the actual tile is smaller.
• Forgetting that diagonal layouts waste more tile.
• Starting the layout at a wall and ending with thin slivers at the opposite side.
• Setting large-format tile on a subfloor that is not flat enough.
• Not mixing tiles from several boxes, which causes visible shade patches.

Waste factor

10% covers cuts and breakage on a straight layout. Use 15% for diagonal or herringbone patterns and large-format tile, and up to 20% for small rooms with many cuts. Keep leftovers: discontinued tile is hard to match later.

Imperial and metric

Switch the toggle above the inputs to enter ft ↔ m, in ↔ cm. The page converts metric entries to imperial before calculating, using NIST factors (1 ft = 0.3048 m, 1 in = 2.54 cm), and shows key results in both systems.

Worked examples

Bathroom floor, 12 × 12 tile

Inputs: area length 10 ft; area width 8 ft; tile length 12 in; tile width 12 in; grout joint 0.125 in; tiles per box 10; waste factor 10%.

Result: You need 87 tiles.

• Units to buy (rounded up): 9 boxes
• Area: 80 sq ft (7.4 m²)
• Coverage per tile incl. joint: 1.021 sq ft
• Tiles before waste: 79
• Boxes to buy: 9

Kitchen, 24 × 12 porcelain

Inputs: area length 16 ft; area width 12 ft; tile length 24 in; tile width 12 in; grout joint 0.125 in; tiles per box 8; waste factor 15%; cost per unit $46.

Result: You need 109 tiles.

• Units to buy (rounded up): 14 boxes
• Area: 192 sq ft (17.8 m²)
• Coverage per tile incl. joint: 2.031 sq ft
• Tiles before waste: 95
• Boxes to buy: 14
• Estimated material cost: $644.00

Shower wall, 3 × 6 subway

Inputs: area length 5 ft; area width 8 ft; tile length 6 in; tile width 3 in; grout joint 0.0625 in; tiles per box 80; waste factor 10%.

Result: You need 342 tiles.

• Units to buy (rounded up): 5 boxes
• Area: 40 sq ft (3.7 m²)
• Coverage per tile incl. joint: 0.129 sq ft
• Tiles before waste: 311
• Boxes to buy: 5

Quick reference for common sizes

The table repeats the first worked example at smaller and larger sizes, keeping every other setting the same, so you can see how the tile calculator result scales.

Limitations

The estimate assumes a rectangular area and uniform tiles. Mosaics on mesh sheets are sold by the sheet or square foot instead. Borders, niches and trim pieces such as bullnose need separate counts.