Construction
Tile Calculator
Enter your area and tile size to get the number of tiles and boxes to buy, including a waste allowance for cuts and breakage — the reason tile orders should never match the bare floor area.
Quick answer: Tiles needed = (area ÷ area per tile) × (1 + waste). A 120 sq ft floor in 12×12-inch tile with 10% waste needs 132 tiles — about 14 boxes at 10 tiles a box. Use 15% waste for diagonal layouts.
- Floor area80.0 sq ft
- With 10% waste88.0 sq ft
- Boxes to buy9
Use 10% waste for straight layouts and 15% or more for diagonal or herringbone patterns and rooms with many cuts. Grout, thinset, and spacers are not included in this count.
How it works
1. Measure the area
Multiply the length and width of the floor or wall in feet. Subtract large openings like a tub surround or vanity only if you're confident — extra tile is far cheaper than a second delivery.
2. Divide by the tile's coverage
Each tile covers its own area: a 12×12-inch tile is exactly 1 sq ft, an 18×18 covers 2.25, a 12×24 covers 2. The calculator divides your area by that coverage.
3. Add waste and round up to boxes
Cuts, breakage, and pattern matching consume extra tile — 10% for straight layouts, 15% or more for diagonal or herringbone. The result rounds up to whole boxes based on tiles per box.
Frequently asked questions
How many tiles do I need for 100 square feet?
In 12×12-inch tile with 10% waste, 110 tiles. In 18×18 tile, about 49 tiles; in 12×24 plank tile, about 55. Always round up to full boxes and keep a few spares for future repairs.
How much extra tile should I buy for waste?
10% for a straight grid layout in a simple room; 15%+ for diagonal, herringbone, or rooms with many corners and cuts; and up to 20% for large-format tile in small spaces, where every cut wastes more of each tile.
How many tiles come in a box?
It varies by size and brand — commonly 6 to 12 for large formats and 10+ for 12×12. Check the box's listed coverage in square feet and set the tiles-per-box field to match your product.