Tile Calculator

How tile quantities are calculated

Each tile covers its own face plus its share of the grout joint around it, so the calculator works with an "effective" tile size — the tile plus one grout gap in each direction:

Effective tile area = (tile length + gap) × (tile width + gap) ÷ 144 sq ft
Tiles needed = area (sq ft) ÷ effective tile area, rounded up

Counting the gap matters more than people expect: with small tiles like 2-inch mosaics or subway tile, grout joints can account for several percent of the finished surface, and a no-gap estimate will leave you short.

How much waste should I add? Ten percent is the standard allowance for a straight (stacked or offset) layout in a rectangular room — it covers edge cuts, breakage, and a few spares. Go to 15% for diagonal, herringbone, or chevron layouts, rooms with lots of corners and obstacles, or large-format tile where one bad cut wastes a big piece. Keep at least a few leftover tiles from the same production lot for future repairs; dye lots vary and the same tile bought later may not match.

Buying by the box? Boxes list their coverage in square feet and tile count on the label — enter the tile count per box above and buy whole boxes, rounding up. If your box lists coverage only, divide that coverage by the effective tile area above to get the count per box.