Tile Calculator
How many tiles and boxes you need for a floor or wall, with a waste allowance for cuts and breakage.
Tile is sold by the box, but rooms are not built to box dimensions. The gap between "the floor is 120 sq ft" and "the right number of boxes" is where most budgets leak — you either run short mid-job and discover the dye lot is gone, or you pay for three boxes that sit in the garage forever.
This calculator converts room dimensions into a tile count, then rounds up to whole boxes. The waste allowance defaults to 10%, which covers standard straight-lay cuts. Raise it to 15% for diagonal layouts, herringbone, or any room with more than four corners — those patterns can waste 20% or more on small-format tile.
How this calculator works
Every field is editable and the result updates as you type — nothing is submitted anywhere, all the maths runs in your browser. That matters for a number you are about to spend money on: you can see exactly which input moved the answer, and by how much.
What this calculation assumes
Assumes a rectangular floor or wall measured at its longest points, and that offcuts are large enough to reuse. Diagonal layouts, mosaic sheets and rooms broken up by cabinetry all need a higher waste figure than the default.
Treat the result as an order-of-magnitude check rather than a final quantity. Product packaging changes, regional labour rates vary by a factor of two, and no calculator has seen your actual site.
Frequently asked questions
How much extra tile should I buy?
10% for a simple rectangular room laid straight, 15% for diagonal or herringbone patterns, and 20% for small tiles (under 4 inches) or rooms with many corners, niches and doorways. Keep one spare box sealed — future repairs will match only if it comes from the same dye lot.
Do I measure the floor or the walls?
For a floor, use the room length and width. For a shower wall or backsplash, measure the height and width of that surface only — do not include the floor. If you are tiling several separate surfaces, run the calculator once per surface and add the box totals.
How many tiles are in a box?
It varies by format. Large-format 24x24 tile often ships 4 per box; 12x24 commonly 6 to 8; subway tile 40 to 60. Check the box label or the product page — the sq ft per box is the number that matters, and it is printed on every carton.
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