Tile Calculator
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What Your Result Means
- Total Area: The square footage of the surface you plan to tile. This is the basic length × width measurement of your floor, wall, or backsplash.
- Tiles Needed: The total number of individual tiles after accounting for grout spacing and waste. Grout lines reduce the effective coverage of each tile, meaning you need slightly more tiles than a simple area division would suggest.
- Boxes (10/box): Standard boxes typically hold 10 tiles. The box count is rounded up so you always have enough. Buy an extra box for future repairs — matching dye lots later can be difficult.
How This Calculator Works
You enter the area dimensions in feet, the tile size in inches, grout line width, and a waste percentage. The tool adds grout spacing to the tile dimension, calculates effective tiles per square foot (144 ÷ tile-with-grout²), multiplies by total area, applies the waste factor, and rounds up. Boxes assume 10 tiles each. It does not account for diagonal layouts or non-square tiles, which typically require more waste.
Quick Questions
How much waste should I plan for?
Ten percent is standard for straight layouts in rectangular rooms. Diagonal patterns, herringbone, or rooms with many cuts (around toilets, doorways, cabinets) should use 15%. Complex patterns or irregular spaces may need up to 20%.
What is a typical grout spacing?
For most floor tiles, 1/8 inch (0.125 in) is a common grout line width. Large-format tiles (18" and above) often use 1/16 inch, while natural stone may use 3/16 inch. The tile manufacturer usually recommends a specific spacing.
Does this work for non-square tiles like subway tiles?
This calculator assumes square tiles. For rectangular tiles, a more precise calculation would account for different row and column spacing. As an approximation, you can use the tile's shorter dimension and increase the waste factor to 15–20%.
Why should I buy extra tiles for later?
Tile production runs (dye lots) vary slightly in color and finish. If a tile cracks or chips years later, replacement tiles from a new batch may not match exactly. Keeping a few spares from the original purchase ensures a perfect match for repairs.
Sources
- Tile Council of North America (TCNA) (tile installation standards, grout joint sizing)
- National Tile Contractors Association (NTCA) (best practices for tile layout and waste estimation)
- Wikipedia — Thinset (tile adhesive coverage rates and application methods)
Method & review
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.