How to Calculate Tile Quantities
To find how many tiles you need, divide the total surface area by the area of one tile (including the grout joint). Always add a waste factor to cover cut tiles and breakage. Use 5% for straight layouts, 10% for standard installations, 15% for diagonal patterns, and 20% for irregular room shapes with many cuts.
Grout joint width affects tile count more than you might expect in large rooms. A 12×12 inch tile with a 3/16 inch grout joint has a true footprint of 12.1875×12.1875 inches. Over a 200 sq ft room, the difference adds up to a few tiles. Always include grout width in your calculation to avoid running short near the finish line.
Frequently Asked Questions
It varies by tile size and manufacturer. The box label always shows the number of tiles and the total square footage per box. Use the sq ft figure for quick ordering.
Bathrooms often have more cuts around pipes and fixtures (10–15%), while kitchens with simpler layouts need only 5–10%. Use higher allowances for irregular spaces.
Specialty patterns generate more offcuts. Use a 15–20% waste factor and check the manufacturer's layout guide for specific pattern requirements.