How Many Tiles Do I Need? The Complete Tile Buying Guide
Buy too few and you make a second trip with a potentially different dye lot. Buy too many and waste money. Here is the formula.
Area (sq ft) / Tile size (sq ft) × Waste factor = Tiles needed. A 100 sq ft bathroom floor with 18×18 inch tiles (2.25 sq ft each) at 10% waste: 100 / 2.25 × 1.10 = 49 tiles. Round up to full boxes. If boxes contain 8 tiles: 49/8 = 6.1, round up to 7 boxes. Always buy from the same lot number — different production runs have subtle color variations visible when installed side by side.
Waste Factor Guide
Simple rectangle, straight layout: 10% waste. Room with many cuts (L-shaped, around fixtures): 15%. Diagonal layout: 15%. Herringbone or complex pattern: 20%. Subway tile on walls: 10-12%. Mosaic sheets: 5-8% (less waste because sheets flex around cuts). The waste goes to partial cuts, breakage during installation, and chips. Save 3-4 extra tiles for future repairs.