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This tile calculator tells you how many tiles you need for a floor, wall, shower or backsplash, how many boxes to buy and roughly how much grout to get. It accounts for the tile size, the grout joint between tiles and a waste allowance for cuts and breakage.
How to Use the Tile Calculator
- Enter the length and width of the area you will tile.
- Enter the tile length and width. For a square tile, both values are the same.
- Enter the grout joint width. Floors often use 1/8–1/4 in (3–6 mm); rectified tiles can use 1/16 in (1.5–2 mm).
- Enter the tile thickness, which is used for the grout estimate.
- Set the waste allowance and the number of tiles in a box.
Tile Formula
Tiles = Area ÷ ((Tile length + Joint) × (Tile width + Joint))
The joint is added to each tile dimension because every tile takes up its own size plus one grout line. The result is then increased by the waste allowance and rounded up to whole tiles and whole boxes.
Grout is estimated with the formula used by most grout manufacturers:
Grout (kg per m²) = (L + W) ÷ (L × W) × Joint width × Tile thickness × 1.6
Here L and W are the tile length and width in millimeters, and 1.6 is the approximate density of cement grout. The calculator adds 10% to this figure.
Worked Example: 10 × 10 ft Floor with 12 × 12 in Tiles
- Area: 100 sq ft
- Space per tile with a 1/8 in joint: 12.125 × 12.125 in = 1.02 sq ft
- Tiles: 100 ÷ 1.02 = 98 tiles
- With 10% waste: 108 tiles, or 11 boxes of 10
- Grout: about 7 lb for 3/8 in thick tiles
Metric example: a 3 × 3 m floor using 30 × 30 cm tiles with 3 mm joints needs about 99 tiles, or 108 with 10% waste.
Tiles per Square Foot and Square Meter
| Tile size | Tiles per sq ft | Tiles per m² (approx.) |
|---|---|---|
| 3 × 6 in subway | 8 | 86 |
| 4 × 4 in | 9 | 97 |
| 6 × 6 in | 4 | 43 |
| 12 × 12 in | 1 | 10.8 |
| 12 × 24 in | 0.5 | 5.4 |
| 24 × 24 in | 0.25 | 2.7 |
| 30 × 30 cm | ≈1.03 | 11.1 |
| 60 × 60 cm | ≈0.26 | 2.8 |
These figures ignore grout joints and waste, so the calculator result will be slightly different and more accurate.
How Much Extra Tile Should I Buy?
- 10% for straight layouts in simple rooms.
- 15% for diagonal layouts or rooms with many cuts.
- 15–20% for large-format tiles, herringbone or natural stone with color variation.
- Keep a few spare tiles for future repairs; finding a match years later is difficult.
Tiling Tips
- Buy all tiles from the same batch or lot number to avoid shade differences.
- Dry-lay a row before you start to plan where cut tiles will fall.
- Large tiles need a very flat substrate; check for dips with a straightedge.
- Covering the rest of the floor with planks? Use our flooring calculator.
Frequently Asked Questions
How do I calculate how many tiles I need?
Divide the area by the space each tile covers including its grout joint, then add 10–15% for waste and round up. The calculator does this automatically for any tile size.
How many 12×12 tiles do I need for 100 square feet?
Without grout joints you need 100 tiles. With 1/8 in joints, about 98 tiles, and with 10% waste you should buy about 108 tiles.
How many tiles are in a square meter?
It depends on the tile size. For 30 × 30 cm tiles you need about 11 per square meter, and for 60 × 60 cm tiles about 2.8 per square meter, before waste.
How much grout do I need?
Grout depends on tile size, joint width and tile thickness. Small tiles with wide joints use much more grout than large tiles with narrow joints. The calculator gives an estimate using the standard manufacturer formula.
Does the grout joint really change the tile count?
Yes, slightly. Each grout line adds to the space a tile covers, so you need a few fewer tiles. The effect is larger for small tiles and wide joints.
Related guide: How Many Tiles Do I Need for a Bathroom Floor or Shower?
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