A tile calculator estimates the number of tiles needed to cover a floor or wall area based on the room dimensions, tile dimensions and a waste percentage. The waste allowance accounts for tiles that need to be cut to fit edges, corners and around obstacles, as well as any breakages during installation.

1. Enter the room length and width in metres.
2. Enter the tile length and width in centimetres.
3. Enter a waste percentage (typically 10% for straight lay, 15% for diagonal).
4. Click Calculate.

Room: 4m × 3m = 12 m² | Tile: 30cm × 30cm = 0.09 m²
Tiles exact: 12 ÷ 0.09 = 133.3 | With 10% waste: 147 tiles

Always round up to the nearest whole tile — you cannot buy a fraction of a tile. Add extra waste for diagonal patterns (15–20%), complex shapes (15–20%) or large format tiles (10–15%). It is better to buy slightly more than needed and keep spares for future repairs.

• Not adding a waste factor — cutting tiles always produces waste.
• Entering tile dimensions in metres instead of centimetres (or vice versa).
• Forgetting to account for grout joints, which slightly reduce the effective tile coverage area.

What waste percentage should I use?

For a straight lay pattern: 10%. For a diagonal or herringbone pattern: 15–20%. For complex shapes or large format tiles: 15%. When in doubt, use 15%.

Should I include grout joints in the calculation?

For most practical purposes, grout joints are small enough to ignore. For very large tiles with wide joints, you may want to add 1–2% extra to account for the joint width.