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Measure the room and get the tiles and boxes to buy with the right waste for your pattern — then the grout, thinset, backer board, spacers, self-leveler and the weight of the finished floor.
With these inputs:
| Result | Value |
|---|---|
| Tiles to buy | 66 tiles |
| Room area | 120 sq ft |
| Area including waste | 132 sq ft |
| One tile covers | 2 sq ft |
| Boxes needed | 9 boxes |
| Waste applied | 10% |
Round up to full boxes and keep one spare box from the same dye lot.
<> The math is simple: room area ÷ area of one tile, then add waste. A 12" × 24" tile covers 2 sq ft, so a 120 sq ft floor needs 60 tiles before waste and 66 tiles at 10% waste. Straight/grid layouts: 10% waste. Diagonal: 15% — every perimeter tile becomes two triangles. Herringbone: 20% — the most cut-heavy common pattern. Buy in full boxes. Keep one unopened box for future repairs; matching tile two years later is usually impossible.
Each 12x24 tile covers 2 square feet, so 100 sq ft needs 50 tiles before waste — about 55 tiles with a 10% waste allowance for cuts.
Add 10% for a straight layout, 15% for diagonal, and 20% for herringbone or busy patterns. Add another 5% if the room has many jogs, closets, or curved cuts.
Buy by square footage in full boxes — that is how tile is sold. Use the tile count to sanity-check the store's box math.
Need the whole roof at once? The free roofing calculator works out roof area, squares, shingle bundles, underlayment, drip edge, ridge cap and installed cost from one set of measurements.