How to use this tile calculator
- Measure the length and width of the floor or wall.
- Enter the tile size (ignore grout lines, they make little difference).
- Use 10% waste for straight layouts and 15% for diagonal or large-format tiles.
- Optionally enter tiles per box to get the number of boxes.
Example
An 8 × 5 ft bathroom floor is 40 sq ft (3.72 m²). With 12 × 24 in tiles and 10% waste you need 22 tiles. If a box holds 8 tiles, that is 3 boxes, and it is worth keeping one or two spare tiles for future repairs.
What to know before you buy
Choosing the waste allowance
Straight layouts in simple rooms need about 10% extra. Diagonal, herringbone and chevron patterns need 15–20% because of the many angled cuts. Large-format tiles also waste more at the edges, and fragile natural stone may need extra for breakage.
Other materials to plan
Besides tile you will need thinset mortar (typically a 50 lb bag covers roughly 40–95 sq ft depending on trowel size and tile), grout (use our grout calculator), spacers, and for wet areas a waterproofing membrane. Check the tile's rating: floor tiles must be rated for foot traffic.
Tiles needed for 100 sq ft (with 10% waste)
| Tile size | Tiles needed |
|---|---|
| 4 × 4 in | 990 |
| 6 × 6 in | 440 |
| 3 × 6 in subway | 880 |
| 12 × 12 in | 110 |
| 12 × 24 in | 55 |
| 18 × 18 in | 49 |
| 24 × 24 in | 28 |
| 6 × 36 in plank | 74 |
Formula
Tiles = area × (1 + waste) ÷ area of one tile, rounded up.
Tips from the pros
- Buy all tiles from the same dye lot: colors can vary between batches.
- Dry-lay a row before setting to plan cuts and avoid thin slivers at the walls.
- Large tiles (15 in and up) need a very flat floor; check with a straightedge first.
Common mistakes to avoid
- Forgetting that a 12 × 24 in tile covers 2 sq ft, so it needs half as many tiles as 12 × 12.
- Skipping waste for diagonal layouts, which need about 15% extra.
Frequently asked questions
How much extra tile should I buy?
10% for standard layouts, 15% for diagonal patterns, and keep a few spare tiles for future repairs.
How many 12×12 tiles do I need for 100 square feet?
100 tiles plus waste, so about 110.
How many tiles are in a square foot?
One 12 × 12 in tile, two 6 × 12 in tiles, four 6 × 6 in tiles or nine 4 × 4 in tiles per square foot.
Should I include grout lines when calculating tiles?
For most tile sizes grout lines make little difference; the waste allowance covers it. For small mosaic tiles, use the sheet size instead.