How to use
- Enter the length × width of the surface in feet, or switch to Area if you already know the square footage. Use m · mm for metric.
- Enter the tile size and the grout joint in inches (1/8 in = 0.125).
- Set the waste allowance: about 10% for a straight lay, 15% or more for diagonal or herringbone patterns with more cuts.
- Add the tiles per box from the carton to see how many boxes to buy.
Formulas
| Item | Formula |
|---|---|
| Area per tile | (tile width + grout) × (tile length + grout) |
| Tiles needed | area ÷ area per tile × (1 + waste%), rounded up |
| Straight grid | ⌈(length + grout) ÷ (tile width + grout)⌉ × ⌈(width + grout) ÷ (tile length + grout)⌉ |
| Boxes | tiles needed ÷ tiles per box, rounded up |
Grout makes each tile cover slightly more area, so it lowers the count a little. The larger the tile, the smaller the effect.
Example
A 10 × 8 ft bathroom floor (80 sq ft) with 12 × 24 in tiles and 1/8 in grout:
- Area per tile: 12.125 × 24.125 ÷ 144 = 2.03 sq ft → 39.4 tiles with no waste
- With 10% waste: 39.4 × 1.1 = 43.3 → 44 tiles
- At 8 tiles per box: 6 boxes (48 tiles)
- Straight grid: 10 × 4 rows = 40 tiles, counting cut edge pieces as whole tiles
Things to watch
- Buy for the larger of the two counts. In small rooms or with large tiles, edge cuts can waste more than the percentage allowance.
- Tiles vary slightly in shade between production lots, so buy spares from the same lot for future repairs.
- For walls, subtract doors, windows and the tub area, and add up each wall separately.
FAQ
How many 12 × 12 tiles are in 100 square feet?
Without grout, each tile is exactly 1 sq ft, so 100 tiles — 110 with 10% waste. Grout lowers the exact figure slightly.
Can I convert between square feet and square meters?
Yes — use the area converter. For painting the walls, try the paint calculator.