Tile math
Tiles = room area ÷ tile area, with the grout line effectively making each tile occupy slightly more space — the calculator accounts for it. Then add waste: 10% is the standard safety margin (cutting, breakage, future repairs); diagonal layouts need 15%, patterned layouts up to 20%.
Example
10×8 ft room = 80 ft². 12×12 in tiles (1 ft² each) with 1/8 in grout → ~79 tiles + 10% waste = 87 tiles ≈ 9 boxes of 10. At $35/box: $315.
Buying tips
- Buy all at once — dye lots vary between batches; a second order may not match.
- Keep 2–3 spare tiles after the job for future repairs; the waste % covers cutting, not future fixes.
- Order the calculator's box count, not less — running out mid-job means a visible mismatch.
- Subtract doors/vanities from the room area if they're large (over ~10 ft²); skip it for small cutouts.
Part of the home-improvement set — see Concrete, Paint and Rug Size calculators for the rest of the room.
Frequently Asked Questions
Q: How do I calculate how many tiles I need for a floor or wall?
Multiply the length by width of the room to calculate total square footage (or square meters), then divide by the square footage covered by one single tile. Always add 10% to 15% extra for cuts, corners, and waste.
Q: How many square feet does a box of tiles cover?
Standard tile boxes typically cover between 10 and 15 square feet (or ~1 to 1.5 m²). For example, 12"×12" tiles usually come with 10–15 tiles per box, covering 10–15 sq ft.
Q: How much extra tile should I buy for cutting waste?
Standard rectangular grid layouts require 10% extra for waste. Diagonal, herringbone, or chevron patterns require 15% to 20% extra due to extensive angled corner cuts.