How to Calculate Tile Quantity
Tile quantity depends on three things: the floor area, the tile size, and the waste factor. Here's the step-by-step process to calculate exactly how many tiles (and boxes) you need.
Step 1: Calculate Room Area
For a rectangular room, multiply length × width:
Room area = length × width (sq ft)
A 12 × 10 ft room = 120 sq ft.
Step 2: Calculate Tile Area
Tiles are measured in inches. Convert to square feet by dividing by 144 (the number of square inches in a square foot):
Tile area = (tile length × tile width) ÷ 144 (sq ft)
A 12 × 12 inch tile: (12 × 12) ÷ 144 = 1.0 sq ft per tile.
A 24 × 24 inch tile: (24 × 24) ÷ 144 = 4.0 sq ft per tile.
A 6 × 6 inch tile: (6 × 6) ÷ 144 = 0.25 sq ft per tile.
Step 3: Calculate Tiles Needed
Divide room area by tile area, rounding up:
Tiles needed = ceil(room area ÷ tile area)
120 sq ft ÷ 1.0 sq ft per tile = 120 tiles (for 12 × 12 tiles).
120 sq ft ÷ 4.0 sq ft per tile = 30 tiles (for 24 × 24 tiles).
Step 4: Add Waste Factor
Tile waste covers cuts at edges, breakage during cutting, and future repairs:
- 10% (default): Straight-lay pattern in a rectangular room
- 15%: Diagonal or herringbone patterns
- 20%: Natural stone with color variation, or large-format tile on uneven subfloor
Tiles with waste = ceil(tiles needed × (1 + waste %))
120 × 1.10 = 132 tiles.
Step 5: Convert to Boxes
Check the box label for tiles per box. Then:
Boxes = ceil(tiles with waste ÷ tiles per box)
With 10 tiles per box: ceil(132 ÷ 10) = 14 boxes.
Nominal vs Actual Tile Size
Tile dimensions are nominal — actual size is typically 1/8" smaller. A "12 × 12" tile may measure 11.875 × 11.875 inches. The calculator uses your entered dimensions, so use the nominal size on the box label for consistency.
Use the Tile Calculator
The Tile Calculator handles all of these steps automatically, including the optional tiles-per-box conversion. For waste factor guidance, see the How Much Tile Waste Should I Buy? guide.