Tile Calculator

Tiling a floor or wall requires calculating the exact area to cover, adding waste for cuts and breakage, and then converting that into a tile quantity and materials cost.

Formula: Area to Tile = Length × Width (for rectangular rooms) Tile Area = Tile Length × Tile Width Tiles Needed = Area ÷ Tile Area × (1 + Waste Factor)

Leave the tile width blank for a square tile. Fill both in for subway, plank, or any other rectangular format.

What each variable means:

• Area to Tile: total square footage or square meters of the surface being tiled. Subtract fixed fixtures (toilets, vanities) if applicable.
• Waste Factor: extra tiles ordered to account for cuts at edges, corners, and breakage. Standard recommendation: 10% for straight lay, 15% for diagonal lay, 20% for complex patterns.
• Tile Area: a 12×12 inch tile = 1 sq ft; a 30×60 cm tile = 0.18 m².
• Grout coverage: one 25 lb bag of sanded grout covers approximately 50–70 sq ft depending on joint width and tile size. This calculator uses 60 as the working middle.
• Adhesive coverage: one 50 lb bag of thin-set mortar covers roughly 40–50 sq ft with a 1/2 inch notched trowel, and much more with a smaller notch.

Standard tile sizes and use cases:

• 12×12 in (30×30 cm): bathroom floors, small kitchens
• 18×18 in (45×45 cm): living rooms, larger spaces
• 24×24 in (60×60 cm): large open-plan areas
• 3×6 in subway tile: backsplashes, shower walls
• 4×16 in plank tile: modern wood-look floors

Worked example: Bathroom floor: 8 ft × 10 ft = 80 sq ft. Using 12×12 inch tiles, waste factor 10%. A 12×12 tile is exactly 1 sq ft, so: 80 ÷ 1 = 80 tiles, × 1.10 = 88 tiles. Grout: 80 ÷ 60 = 2 bags.

Switch to 3×6 subway tile and the arithmetic changes sharply. Each tile is 18 sq in, or 0.125 sq ft, so the same floor takes 80 ÷ 0.125 = 640 tiles before waste. Small tile means far more pieces and far more cutting, which is why the waste factor climbs with a running-bond or herringbone layout.

Always buy 10–15% extra and keep the leftovers. Future repairs need matching tiles, and discontinued styles cannot be matched later at any price.