Tile Calculator
Your details
Advanced options
Result
Boxes to buy
- Tiles needed
- 52 including waste
- Area to tile
- 96 sq ft
- Waste allowance
- 10% for a straight layout
- Spare tiles after cutting
- 8 tiles
- Coverage per tile
- 2.031 sq ft each, including the grout joint
- Tile is sold in whole boxes, so 7 boxes gives 56 tiles against the 48 needed to cover the floor. Keep the surplus — a discontinued tile cannot be matched later, and a cracked tile in three years needs a replacement from the same batch.
Tile count by tile size
The same area in each common format, at this layout's waste allowance.
| Tile size | Coverage each | Tiles needed |
|---|---|---|
| 12 × 12 in | 1.021 sq ft | 104 |
| 12 × 24 in | 2.031 sq ft | 52 |
| 18 × 18 in | 2.281 sq ft | 47 |
| 24 × 24 in | 4.042 sq ft | 27 |
| 6 × 24 in plank | 1.026 sq ft | 103 |
| 3 × 6 in subway | 0.133 sq ft | 795 |
Waste by layout pattern
| Pattern | Waste | Tiles needed |
|---|---|---|
| Straight / stacked | 10% | 52 |
| Offset / running bond | 10% | 52 |
| Diagonal | 15% | 55 |
| Herringbone | 20% | 57 |
How many tiles do I need?
To work out how many tiles you need, divide the area in square feet by the coverage of one tile including its grout joint, then add 10% for cutting waste. A 96 square foot floor in 12 × 24 inch tile needs about 51 tiles.
tiles = (area_sqft ÷ ((w + g)(h + g) ÷ 144)) × (1 + waste)- area
- Surface area in square feet
- w, h
- Tile width and length in inches
- g
- Grout joint width in inches
- 144
- Square inches in a square foot
- waste
- 0.10 straight, 0.15 diagonal, 0.20 herringbone
Each tile covers its own footprint plus one grout joint along two sides, so the effective tile size is slightly larger than the nominal one — a 12 by 24 inch tile with a 1/8 inch joint covers 2.02 square feet rather than 2.00. That difference is small and goes the right way, reducing the count marginally. The waste factor is where the real money is. It is not padding: on any tiled floor every tile around the perimeter is cut, and the offcut is usually unusable because the next cut needs a different dimension. A straight layout wastes about 10%, a diagonal 15% because every edge tile is cut at 45 degrees, and herringbone 20%. The last step is boxes. Tile is sold in whole boxes only, so the real purchase rounds up again — and keeping the surplus matters, because a discontinued line cannot be matched when a tile cracks in three years.
- Measure the area to tile in feet and multiply for square footage.
- Add the grout joint to the tile's width and length.
- Multiply those and divide by 144 for coverage per tile.
- Divide the area by the coverage per tile.
- Add 10 to 20% for cutting waste, depending on layout.
- Round up to whole boxes using the tiles-per-box figure.
Worked example: A 12 × 8 ft floor in 12 × 24 in tile with 1/8 in grout, straight layout, 8 tiles per box
A 12 × 8 ft floor in 12 × 24 in tile with 1/8 in grout, straight layout, 8 tiles per box
The floor is 12 × 8 = 96 square feet. Each tile covers (12 + 0.125) × (24 + 0.125) = 292.5 square inches, which divided by 144 is 2.031 square feet. So bare coverage needs 96 ÷ 2.031 = 47.3 tiles, call it 48. Adding the 10% straight-layout waste gives 52 tiles. At 8 tiles a box that is 6.5 boxes, so you buy 7 — which is 56 tiles, leaving 8 spare after the 48 that actually go down. Switching to a herringbone layout would push the waste to 20% and the requirement to 57 tiles, which is 8 boxes. That one decision costs an extra box, and it is the step most people skip when pricing a job from a tile sample alone.
What each tile input means
- Area length
- The longer dimension of the surface you are tiling, in feet.
- Area width
- The shorter dimension, in feet. For a wall, this is the height.
- Tile width
- The tile's short side in inches. Nominal sizes are usually accurate enough.
- Tile length
- The tile's long side in inches. For a square tile, the same as the width.
- Grout joint
- The gap between tiles, in inches. One eighth is standard for floors, one sixteenth for rectified tile. The joint makes each tile cover slightly more area.
- Layout pattern
- The pattern drives the cutting waste. Anything laid at an angle produces more offcuts, because every tile at the perimeter has to be cut.
- Tiles per box
- From the box label. Tile is sold in whole boxes, so this is what decides your actual purchase.
- Price per box
- Optional, for a cost total.
What this tile does not account for
- Boxes, not tiles, are what you buy. The box count rounds up again after the waste allowance, so the real surplus is usually larger than the waste factor suggests.
- Keep the spare tiles. A discontinued line cannot be matched, and dye lots vary between batches even within a current range — a replacement bought in three years will not match.
- Waste allowances assume a reasonably simple perimeter. A room with many alcoves, a curved edge or numerous fixtures to cut around needs more, sometimes 25%.
- Trim pieces, bullnose edging, transition strips and thresholds are separate purchases and are not counted here.
- Grout, thinset and backer board are not calculated. Coverage for those depends on tile size and trowel notch, and is stated on the bag.
- Nominal tile sizes are not always actual. A "12 inch" tile is often 11.8 in; over a large floor the difference accumulates, though rarely enough to change the box count.
Frequently asked questions
How many tiles do I need for 100 square feet?
About 50 tiles in 12 × 24 inch format, or 110 in 12 × 12, both including 10% waste. Divide 100 by the coverage of one tile including its grout joint, then add the waste allowance.
How much extra tile should I buy for waste?
Ten percent for a straight or offset layout, fifteen for diagonal, and twenty for herringbone. Angled patterns waste more because every perimeter tile is cut at an angle and the offcut is rarely reusable.
Does the grout joint change how many tiles I need?
Slightly, and in your favour. Each tile covers its own size plus one joint on two sides, so a 12 × 24 tile with a 1/8 inch joint covers 2.03 square feet rather than 2.00.
Why should I keep leftover tiles?
Because tile lines get discontinued and dye lots vary between batches. A cracked tile in three years needs a replacement from the same batch, and the only reliable source is the box in your garage.
How many 12x12 tiles are in a box?
Usually 8 to 12, but it varies by manufacturer and tile thickness. The box states both the tile count and the square footage it covers — use the figure on the box, not a general assumption.
Can I tile without grout joints?
Only with rectified tile, and most manufacturers still require a minimum 1/16 inch gap. Without a joint there is nowhere for movement to go, and the floor will tent or the tiles will crack.
Sources and review
Last reviewed .