Tile Calculator

Calculate how many tiles you need for a floor. Enter room dimensions, tile size, and waste percentage to get tile count, tiles with waste, and boxes required.

ft

Length of the room to be tiled.

ft

Width of the room to be tiled.

in

Length of one tile. Common: 12", 16", 18", 24".

in

Width of one tile. Common: 12", 16", 18", 24".

%

Extra for cuts, breakage, future repairs. Straight-lay: 10%. Diagonal: 15%. Stone/natural variation: 20%.

Optional: check the box label. If left blank, only tile count is shown.

How this calculator works

This tile calculator estimates tile quantity for a rectangular floor in three steps:

  1. Room area: room length × room width (in sq ft).
  2. Tile area: (tile length × tile width) / 144 to convert sq in to sq ft.
  3. Tiles needed: ceil(room area / tile area), then add waste allowance (default 10%).

If you enter tiles-per-box, the calculator also shows the number of boxes to purchase.

Waste guidelines: 10% for straight-lay patterns, 15% for diagonal or herringbone, 20% for natural stone with color variation.

Formula

room_area       = room_length × room_width  (sq ft)
tile_area_in    = tile_length × tile_width  (sq in)
tile_area       = tile_area_in / 144  (sq ft)
tiles_needed    = ceil(room_area / tile_area)
tiles_with_waste = ceil(tiles_needed × (1 + waste_pct / 100))
boxes           = ceil(tiles_with_waste / tiles_per_box)  [if provided]

Example

For a 12 × 10 ft room (120 sq ft) with 12 × 12 inch tiles, 10% waste, 10 tiles per box:

  • room_area = 120 sq ft
  • tile_area = (12 × 12) / 144 = 1.0 sq ft
  • tiles_needed = ceil(120 / 1.0) = 120 tiles
  • tiles_with_waste = ceil(120 × 1.10) = 132 tiles
  • boxes = ceil(132 / 10) = 14 boxes

Important assumptions

  • Tile dimensions are NOMINAL — actual size is typically 1/8" smaller (e.g. a "12×12" tile measures ~11.875"). The calculator uses your entered dimensions.
  • Default waste 10% for straight-lay patterns. Use 15% for diagonal/herringbone, 20% for natural stone.
  • Large-format tiles (24"+) on uneven subfloors break more easily during cuts — increase waste to 15%.
  • Grout and thinset are calculated separately (typically 1 bag thinset per 75-100 sq ft; 1 lb grout per 25-50 sq ft depending on joint width).
  • Always check the box for tiles-per-box count — varies by manufacturer and tile thickness.

FAQ

How many 12×12 tiles do I need for 100 sq ft?
100 tiles for exact fit, or 110 tiles with 10% waste. Each 12×12 tile covers 1 sq ft. For 10% waste (standard straight-lay), order 110 tiles.
How much tile waste should I add?
10% for straight-lay (simple rectangular layouts). 15% for diagonal patterns or herringbone. 20% for natural stone with color variation. Always order extra — running short mid-project means dye-lot mismatch on the replacement tiles.
How do I calculate tiles per box?
Check the box label. Typical: 10 tiles per box for 12×12 ceramic (10 sq ft), 5 tiles per box for 24×24 porcelain (20 sq ft), 40-50 tiles per box for 6×6 wall tile.
Do I need to account for grout lines?
Standard grout lines (1/8" to 1/4") add negligible area. For 12×12 tiles with 1/4" grout, effective tile+grout area is ~12.25×12.25 = 1.02 sq ft — close enough to 1.0 sq ft that the calculator's 10% waste covers it.
What if my room isn't rectangular?
Divide it into rectangles, calculate each separately, and sum the results. For L-shaped rooms, split at the inside corner. For circular or curved areas, use the bounding rectangle and accept ~20% waste.
Should I buy extra tiles for future repairs?
Yes — save 1 box (10-20 tiles) for future repairs. Tile dye-lots vary, so buying from the same lot ensures color match. Store extras flat in a dry location.