The short answer
Tiles needed = area in square inches ÷ one tile's area, plus 10% waste (15% for diagonal or small rooms). A 10 × 8 ft floor with 12 × 12 in tiles needs 80 tiles plus 8 spare = 88.
Running out of tile halfway through a job is worse than overbuying — the next batch rarely matches. Here's how to count properly.
Step by step
- Measure the floor or wall in feet; split L-shapes into rectangles.
- Multiply length × width for square feet, then × 144 for square inches.
- Multiply tile width × length in inches for one tile's area.
- Divide total area by tile area and round up.
- Add 10% for straight layouts, 15% for diagonal or herringbone.
- Divide by tiles per box and round up. Check every box has the same batch number.
What you need
- Tape measure
- Pencil and paper
- Tile spacers
- Notched trowel
What it costs
| Item | Typical cost |
|---|---|
| Ceramic tile | $1–$5 per sq ft |
| Porcelain tile | $3–$10 per sq ft |
| Thinset and grout (100 sq ft) | $40–$90 |
Common questions
Do I subtract the area of the bathtub or vanity?
Yes, if the tile won't go under it. Measure only the visible floor.
How much extra for large-format tiles?
Large tiles break less but waste more on cuts — keep 10–15%.