Tile Calculator
Enter the length and width of the area you want to tile, pick a tile size and a waste allowance, and get the number of tiles you need to buy.
How to calculate how much tile you need
- Measure the length and width of the floor or wall in feet and multiply them to get the area in square feet. For an L-shaped or odd-shaped room, break the space into rectangles, calculate each one and add them together.
- Convert the tile size to square feet: multiply the tile length by the tile width in inches, then divide by 144 (the square inches in a square foot). A 12×12 in tile is exactly 1 sq ft, a 12×24 in tile is 2 sq ft, an 18×18 in tile is 2.25 sq ft and a 6×6 in tile is 0.25 sq ft.
- Add a waste allowance for cuts, breakage and future repairs: 10% for a straight layout, 15–20% for a diagonal (45°) layout, herringbone patterns or rooms with many corners. Divide the adjusted area by the tile area and round up — at the store, also round up to full boxes.
Area (sq ft) = Length (ft) × Width (ft). Tiles = Area × (1 +
waste %) ÷ ((tile length in × tile width in) ÷ 144), rounded
up.
Common tile sizes and coverage
| Tile size | Area per tile | Tiles per 100 sq ft (no waste) |
|---|---|---|
| 6 × 6 in | 0.25 sq ft | 400 |
| 12 × 12 in | 1 sq ft | 100 |
| 12 × 24 in | 2 sq ft | 50 |
| 18 × 18 in | 2.25 sq ft | 45 |
| 24 × 24 in | 4 sq ft | 25 |
Tile is sold by the box — divide your tile count by the pieces per box on the label and round up.
Frequently asked questions
A 10×10 room is 100 sq ft and each 12×12 tile covers exactly 1 sq ft. With a 10% waste allowance you need 110 tiles.
Add 10% for a straight layout in a square room, and 15–20% for diagonal or herringbone layouts, rooms with lots of corners, or brittle natural stone. Keep 2–3 spare tiles after the job for future repairs — dye lots change over time.
The area does not change — only the waste does. Measure the room as usual and set the waste allowance to 15–20%, because every edge tile is cut on an angle and the offcuts cannot be reused.
It varies by size and brand: 12×12 tiles often come 10–15 per box (10–15 sq ft), 12×24 tiles 6–8 per box (12–16 sq ft), and small mosaics are sold by the mesh sheet. Check the coverage printed on the box and round up to full boxes.
Not meaningfully. Nominal tile sizes already assume a grout joint, and actual tiles are slightly smaller (a "12 in" tile is often 11-7/8 in). With typical 1/16–1/8 in grout lines it evens out, so estimate with the nominal size.
Yes — multiply the wall height by its width to get the area. A typical backsplash is 18 in high, so a 10 ft run is 15 sq ft. With 3×6 in subway tile (0.125 sq ft each) that is about 120 tiles plus waste.
A 50 lb bag of thin-set covers roughly 80–100 sq ft with a 1/4 in square-notch trowel (small and medium tiles) or 40–60 sq ft with a 1/2 in trowel (large-format tile). Check the coverage chart on the bag.
A 1/4 × 1/4 in square-notch trowel works for tiles up to 12 in; use 1/4 × 3/8 in for 12–16 in tiles and 1/2 in for large-format tiles 18 in and up. Bigger tiles need a deeper mortar bed for full support.
Split it into rectangles, calculate each area separately and add them together. You can run this calculator once per rectangle or total the square footage first — and use the higher waste setting, since jogs mean more cuts.
Most boxes are labeled with coverage — commonly 10–15 sq ft for 12×12 and 12–16 sq ft for 12×24. Divide your adjusted area (including waste) by the box coverage and round up.