How to Calculate Tiles Required for a Room: Formula & Examples

Ordering too few tiles means a frustrating halt mid-installation while you wait for more — and there's no guarantee the next batch will be the exact same shade. Ordering too many wastes money. Getting the calculation right before you buy takes 10 minutes and saves hours of headache.

The Basic Formula

Number of tiles = Room Area ÷ Tile Area, then add 10% for wastage

Let's work through it step by step.

Step 1: Calculate the Room Area

Measure the length and width of the room in metres. Multiply them together.

Example: Room is 4.5m × 3.8m = 17.1 m²

If the room is L-shaped or irregular, divide it into rectangles, calculate each area separately, and add them together.

Deduct any permanent fixtures that won't be tiled — built-in wardrobes with full-floor bases, kitchen islands that sit on the subfloor, etc. Don't deduct doorways — you need tiles there too.

Step 2: Calculate the Tile Area

Tile sizes are given in mm. Convert to metres: divide by 1,000.

• 600×600mm tile = 0.6m × 0.6m = 0.36 m² per tile
• 300×300mm tile = 0.3m × 0.3m = 0.09 m² per tile
• 400×400mm tile = 0.4m × 0.4m = 0.16 m² per tile
• 600×1200mm tile = 0.6m × 1.2m = 0.72 m² per tile

Step 3: Calculate the Number of Tiles

Divide room area by tile area:

Example: 17.1 m² ÷ 0.36 m² = 47.5 → round up to 48 tiles

Step 4: Add Wastage

For our example: 48 tiles × 1.10 = 52.8 → order 53 tiles (or round to the nearest box)

Worked Examples

Example 1: Living room, 600×600mm tiles

• Room: 5.0m × 4.0m = 20 m²
• Tile area: 0.6 × 0.6 = 0.36 m²
• Tiles needed: 20 ÷ 0.36 = 55.6 → 56 tiles
• With 10% wastage: 56 × 1.1 = 61.6 → 62 tiles

Example 2: Bathroom floor, 300×300mm tiles

• Room: 2.2m × 1.8m = 3.96 m²
• Tile area: 0.3 × 0.3 = 0.09 m²
• Tiles needed: 3.96 ÷ 0.09 = 44 tiles
• With 15% wastage (bathroom, cuts around WC): 44 × 1.15 = 50.6 → 51 tiles

Example 3: Kitchen backsplash, 75×300mm subway tiles

• Wall area: 3.0m × 0.6m = 1.8 m²
• Tile area: 0.075 × 0.3 = 0.0225 m²
• Tiles needed: 1.8 ÷ 0.0225 = 80 tiles
• With 10% wastage: 80 × 1.1 = 88 → 88 tiles

Calculating Wall Tiles

For wall tiles (bathroom walls, kitchen backsplash):

1. Measure total wall area to be tiled (height × width for each wall)
2. Deduct openings: windows, doors, mirror areas, and spaces above/below wall cabinets
3. Divide by tile area
4. Add 12–15% for wastage (wall tiles need more cuts around switches, outlets, taps, and fittings)

How Tiles Are Sold: Boxes vs Individual Tiles

Tiles are sold in boxes, not individually. Each box contains a set number of tiles covering a specified area (printed on the box). Always buy in whole boxes — you can't return part-boxes in most tile shops.

After calculating your tile count, check the box coverage and round up to the nearest complete box. If your calculation says 62 tiles and each box covers 10 tiles, buy 7 boxes (70 tiles) — the extra 8 are your buffer for future replacements if any crack.

Pro Tip: Keep 5–10 tiles from your installation set aside as spares. Store them in a dry location. If a tile cracks or chips in 3 years, matching a replacement to the exact batch shade and texture is very difficult. Having a spare from the original batch means a perfect invisible repair.

Adhesive and Grout Quantities

Tile Installation Labour Costs