How the tile calculator works
Floor area is room length × room width. It is divided by the area of one tile, increased by the waste percentage, then rounded up to whole tiles and boxes.
Waste is extra material for cuts, edges and breakage. A straight layout usually needs 10%; diagonal and herringbone patterns need at least 15%.
Ordering tips
- Check the tiles per box and coverage on the box, not the product photo.
- Buy all boxes in the same batch or shade when possible.
- Keep a few spare tiles for future repairs.
Assumptions
The tile count uses the nominal tile size and does not include grout joints. Borders, niches and skirting are not included.
Last reviewed October 27, 2026
Frequently asked questions
How many 30 × 30 cm tiles cover 20 m²?
About 223 tiles before waste. With 10% waste, plan for 245 tiles.
How much waste should I add?
10% for a straight layout, 15% for diagonal or herringbone. Add more for small rooms, many corners or large tiles.
How many boxes do I need?
Divide the tile count by the tiles per box and round up. Check the box label for the exact coverage.
Does the grout gap change the tile count?
Only slightly. This calculator uses the nominal tile size; follow the layout plan for joint width.