Last updated: March 2026
How to Calculate Tile for Floors and Walls
Calculating tile quantities requires knowing your room dimensions, tile size, and waste factor. Measure your room in feet, calculate the total square footage, then divide by the area of one tile. Always add 15% extra for cuts, breakage, and future replacements.
For wall tile, measure the wall height and width to get wall square footage. Subtract areas for windows, doors, and fixtures. Wall tile waste is often lower than floor tile (10%) because there are fewer cuts around obstacles, though shower niches and corners add complexity.
Our calculator handles all of this automatically — enter dimensions, and it shows tile counts for common sizes (12×12, 18×18, 24×24) with proper waste factored in.
Tile Sizes and Layout Patterns
12×12 inch tiles are the classic standard — easy to handle, cut, and install. Each tile covers exactly 1 square foot, making quantity calculations simple. They work well in bathrooms and smaller spaces where larger tiles would need many cuts.
18×18 and 24×24 inch tiles are increasingly popular for modern looks. Larger tiles mean fewer grout lines, giving a cleaner appearance. However, they require a flatter substrate, a medium-bed mortar, and back-buttering for proper adhesion. Waste is slightly higher because partial cuts create larger unusable pieces.
Popular patterns include straight lay (grid), brick offset, diagonal, and herringbone. Straight lay is the most material-efficient. Brick offset (staggering tiles by 50% or 33%) adds visual interest with minimal extra waste. Diagonal and herringbone patterns create striking results but increase waste by 5-10% due to angled cuts at walls.
Frequently Asked Questions
How do I calculate how many tiles I need?
Measure your room's length and width in feet, multiply them for square footage, then divide by the area of one tile. For 12×12" tiles, each covers 1 sq ft. For 18×18" tiles, each covers 2.25 sq ft. For 24×24" tiles, each covers 4 sq ft. Always add 15% extra for cuts and waste.
Why does tile have a higher waste factor?
Tile requires more waste (15%) than other flooring because tiles at edges and around obstacles must be cut, and the remaining pieces are often too small to reuse. Diagonal and herringbone patterns increase waste further. Complex room shapes with many corners or cuts also increase waste.
What tile size should I choose?
Larger tiles (18×18" or 24×24") make rooms look bigger and have fewer grout lines to maintain. Smaller tiles (12×12") are easier to cut and waste less material. For small bathrooms, smaller tiles work better around fixtures. For large open spaces, bigger tiles look cleaner.
How much mortar do I need for tile?
On average, you'll need about 50 lbs of thinset mortar per 100 sq ft of tile. This varies by tile size, substrate condition, and mortar type. Large-format tiles (over 15") require a medium-bed mortar applied with larger trowel notches. Always back-butter large tiles for full coverage.
Can I tile over existing tile?
Yes, in many cases you can tile over existing tile if the old tile is level, well-bonded, and structurally sound. Clean the surface, lightly sand it for adhesion, and use a suitable bonding mortar. This saves the labor of removal but adds height — check door clearances and transitions.
What's the difference between ceramic and porcelain tile?
Porcelain is denser, harder, and more water-resistant than ceramic tile. Porcelain absorbs less than 0.5% moisture vs 3-7% for ceramic. For outdoor use, showers, or high-traffic areas, porcelain is the better choice. Ceramic is easier to cut and generally less expensive.