Tile Calculator
Calculate how many tiles you need from room size, tile width and height, grout spacing, and waste. Optional tiles per box and material cost.
How to use this tile calculator
Tile quantity is a layout problem, not just area ÷ tile area. Grout joints add a little coverage per tile, and you still round up to full tiles at the walls. Ten percent waste covers cuts and a few extras for later repairs; 15% is safer for diagonal or herringbone.
Enter fractions for grout (1/8) if you like. Mosaic sheets are easier to treat as one “tile” the size of the sheet. Walls use the same math — height is the second dimension. Thinset and grout bags are not included.
Formula
Worked example
A 12×10 ft floor, 12×12 in tile, ⅛ in grout: 144 in ÷ 12.125 ≈ 12 columns, 120 in ÷ 12.125 ≈ 10 rows = 120 tiles. 10% waste → 132 tiles, or 14 boxes of 10.
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Frequently asked questions
How many 12×12 tiles for a 10×10 room?
100 sq ft is 100 tiles before grout and waste. With ⅛ in grout and 10% waste you will still buy a little over 100 — this tool counts the grid including grout.
Does grout reduce the number of tiles?
Slightly. Each tile plus joint covers more than the tile face, so you need fewer pieces than area ÷ tile area, then waste adds some back.
How much tile waste should I add?
10% straight lay, 15% diagonal, more for tiny mosaics or a chaotic layout.
How many boxes of tile?
Divide tiles (with waste) by the count on the carton and round up. Mix boxes for shade variation.
Walls and floors?
Same formula. Use wall height as width.
Results are estimates for informational purposes and are not financial, legal, or professional advice. Last reviewed 2026-08-19.