About the tile calculator
Tile is sold by the box, but you measure rooms in feet. This calculator finds how many tiles fit your area, including the grout joint around each tile, adds a waste allowance for cuts and breakage, and converts the result to boxes.
It works for any rectangular tile, from small mosaics sheets to large-format porcelain.
How to use this calculator
- Measure the area to tile.
- Enter the tile size and grout joint width.
- Choose a waste allowance.
- Enter tiles per box from the packaging to get a box count.
Worked examples
- Area: 100 sq ft
- 12 × 12 in tiles = 1 sq ft each
- 10% waste: 110 tiles
- 10 tiles per box: 11 boxes
Buy 11 boxes.
Measurement guidance
Waste allowance
Straight layouts in simple rooms often use around 10%. Diagonal and herringbone patterns, or rooms with many corners, need more.
Walls
For walls, multiply width by height for each wall and subtract windows and niches.
Frequently asked questions
How many extra tiles should I buy?
A 10% allowance is common for straight layouts, more for diagonal or complex patterns. Keep spares for future repairs, since dye lots can change.
Does grout width matter?
Slightly. Wider joints mean each tile covers a bit more area, so you need a few fewer tiles.
What about mosaic sheets?
Enter the sheet size as the tile size and count sheets instead of individual pieces.