Nothing quite derails a tiling project like discovering mid-floor that you're short on tiles. The replacement order arrives from a different production batch. The colour is subtly off. And now your bathroom floor is a permanent reminder of the calculation error. Tile maths is simple — here's how to do it right.
The Core Calculation
Tiles needed = Area (m²) ÷ Area per tile (m²), plus waste allowance. Example: a 600×600mm tile = 0.36 m². For a 6 m² floor: 6 ÷ 0.36 = 16.7 → round up to 17 before waste. Our tile calculator applies waste automatically. Use our square footage calculator for irregular rooms first.
Waste Allowances by Layout
- Straight grid: +10%
- Brick/offset pattern: +10-15%
- Diagonal (45°): +15-20%
- Herringbone: +15-20%
- Complex L-shaped room: +20%
Planning Your Layout
Centre the layout so cut tiles at opposite edges are equal in size — no cut piece smaller than half a tile. Dry-lay your first row without adhesive before fixing anything. Takes 20 minutes. Prevents hours of rework.
Consumables to Budget For
- Tile adhesive: 2-4 kg/m² depending on tile size
- Grout: 0.5-3 kg/m² depending on joint width
- Grout joint width: 2mm rectified tiles | 3-5mm standard | 10mm+ natural stone
The Batch Number Rule — Critical
Tiles are made in batches. Colour varies between batches — sometimes obviously, sometimes subtly. Always order all tiles at once from the same batch. Check every box for the same batch number when the delivery arrives. If boxes differ, contact the supplier before opening them. Re-ordering from a different batch is the single most common expensive tiling mistake.
Further reading: The Tile Association provides installation standards for professional and domestic tiling. Visit the Tile Association for installation guidance.