Tile Calculator
Calculate how many tiles you need for a floor or wall. Enter room and tile size, add a waste allowance, and get the exact number of tiles to buy.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Show the formula & steps
How the Tile Calculator Works
This calculator tells you exactly how many tiles to buy for a floor or wall. You enter the room length and width (in feet) and the tile dimensions (in inches), choose a waste percentage, and it returns the area, the bare tile count, and the final number to purchase.
Because rooms are measured in feet and tiles in inches, the tool converts the tile size to square feet, divides the room area by it, rounds up to whole tiles, and finally pads the count with your waste allowance.
The Formula
Area to cover (ft²) = room length × room width Tile area (ft²) = (tile width in × tile height in) ÷ 144 Base tiles = ceil( area ÷ tile area ) Tiles to buy = ceil( base tiles × (1 + waste% ÷ 100) )
The 144 converts square inches to square feet (12 × 12 = 144). Both the base count and the final count are rounded up, because you cannot install part of a tile and cuts leave unusable offcuts.
Worked Example
Tiling a 12 ft × 10 ft floor with 12 × 12 inch tiles and a 10% waste allowance:
- Area to cover = 12 × 10 = 120 ft²
- Tile area = (12 × 12) ÷ 144 = 1 ft² per tile
- Base tiles = ceil(120 ÷ 1) = 120 tiles
- Tiles to buy = ceil(120 × 1.10) = 132 tiles
If instead you used 6 × 6 inch tiles, each covers 0.25 ft², so you would need ceil(120 ÷ 0.25) = 480 base tiles, and 528 with 10% waste.
Choosing a Waste Percentage
The right waste allowance depends on the layout and the tile, because more cuts means more offcuts you cannot reuse:
| Layout / situation | Suggested waste |
|---|---|
| Straight grid, square room | 10% |
| Diagonal layout | 15% |
| Herringbone or complex pattern | 15–20% |
| Large-format tiles (cuts waste more) | 15–20% |
| Many corners, niches, or angles | up to 20% |
Buying from the same dye lot keeps color consistent, and keeping a handful of spare tiles lets you replace a cracked tile years later without a visible mismatch. When in doubt, round up to the next full box rather than risk running short mid-job.
Frequently asked questions
How do I calculate how many tiles I need?+
Find the area to cover (room length × width), find one tile's area in the same units, divide the room area by the tile area, round up to a whole tile, then add a waste percentage. For a 12 × 10 ft room with 12 × 12 in tiles, that is 120 ft² ÷ 1 ft² = 120 tiles, plus 10% waste = 132 tiles.
How much waste should I add for tile?+
Add 10% for a simple straight or grid layout, 15% for diagonal or herringbone patterns, and up to 20% for very large tiles, complex rooms, or many cuts. Waste covers breakage, cuts at edges, and future repair spares.
Why divide tile size by 144?+
Tile size is usually given in inches but rooms are measured in feet. There are 144 square inches in one square foot (12 × 12), so dividing the tile's width × height in inches by 144 converts it to square feet to match the room area.
How many 12x12 tiles are in a square foot?+
Exactly one. A 12 × 12 inch tile is 1 square foot, so a 100 ft² room needs about 100 tiles before waste. Smaller tiles like 6 × 6 inch cover 0.25 ft² each, so four of them equal one square foot.
Should I round up the number of tiles?+
Yes. You cannot buy a fraction of a tile, so always round up to the next whole tile, and buy boxes that meet or exceed your total. Keeping a few spares from the same dye lot is wise for future repairs.