What Is a Tile Calculator?
A tile calculator finds how many tiles you need to cover a room, based on room dimensions, tile size, and a waste allowance for cuts and breakage — plus an estimated material cost.
How to Use the Tile Calculator
- Enter your room's length and width in feet.
- Enter your tile's dimensions in inches.
- Enter a waste allowance percentage (10% is typical).
- Optionally enter cost per tile for an estimated total cost.
Tile Calculation Formula
Worked Example
Room area: 12 × 10 = 120 sq ft
Tile area: (12×12)÷144 = 1 sq ft per tile
Tiles needed: 120 ÷ 1 = 120, plus 10% waste = 132 tiles
Understanding Your Results
Tiles Needed includes your waste allowance, so this is the quantity to actually purchase. Room Area and Area Per Tile show the underlying math. Waste allowance accounts for cutting tiles to fit edges, breakage, and future repairs.
Tips for Tile Projects
- Buy slightly more than calculated (10-15%) to account for cuts, breakage, and future repairs matching the same batch/dye lot.
- Diagonal layouts typically require more waste allowance (15-20%) due to more angled cuts.
- Keep leftover tiles for future repairs, since dye lots can vary between production runs.
Common Mistakes to Avoid
- Forgetting to convert tile dimensions from inches to the same unit as room dimensions.
- Underestimating waste allowance for complex layouts or diagonal patterns.
- Not accounting for grout line width, which slightly affects actual coverage per tile.
Frequently Asked Questions
Divide the room's total area by the area of one tile, then add a waste allowance (typically 10%) to account for cuts and breakage.
Most professionals recommend 10% extra for simple, straight layouts, and 15-20% extra for diagonal patterns or rooms with many corners and cuts.
Yes — keeping a few extra tiles from the same batch is wise, since dye lots can vary between production runs, making later replacement tiles potentially not match exactly.
Multiply length by width in inches, then divide by 144 to convert to square feet (since there are 144 square inches in a square foot).
Slightly — wider grout lines mean fewer tiles fit per square foot, though the effect is usually small enough that standard waste allowances typically cover it.