Tiler is measuring up a 4.2m x 3.6m bathroom with a separate 2.1m x 1.8m shower recess. Before the tile order, you need the total tile count with the correct waste allowance for the tile size and a diagonal lay pattern.
Tile Estimator
Tiling
Tiles = (Area ÷ Tile area) × Waste factor
Always round up to full boxes. Order 10–15% extra for future repairs.
Results are estimates for planning purposes. Verify with current standards and a qualified professional.
1 What this calculator does
Calculates the number of tiles required to cover an area from the room dimensions and tile size. Applies waste percentage for different laying patterns (straight, diagonal, complex). Shows total area to purchase and number of boxes based on pack coverage.
2 Formula & professional reasoning
Room area (m²) = Length x Width
Tile area (m²) = Tile length (mm) / 1000 x Tile width (mm) / 1000
Tiles required = Ceiling(Room area x Waste factor / Tile area)
Waste factors: Straight 1.10 | Diagonal/feature 1.15 | Complex 1.20
Tiles are ordered in square metres plus a waste factor. The waste accounts for cuts at walls and corners, breakages during installation, and the offcuts from pattern alignment. Diagonal laying creates larger corner triangles and more cut waste than straight laying. Always round up to full boxes -- buying half a box is impossible and returning leftover boxes is often subject to restocking fees.
3 Worked examples
⚠️ Illustrative example only — not clinical or professional instruction.
Basic
Bathroom floor -- straight lay
Given: Floor area: 4.2m x 3.6m = 15.12 m² | Tile: 600mm x 600mm | Waste: 10% straight lay
Working:
Tile area: 0.6 x 0.6 = 0.36 m² | Tiles net: 15.12 / 0.36 = 42 tiles | With 10% waste: 42 x 1.10 = 46.2 -> 47 tiles | Area to buy: 15.12 x 1.10 = 16.63 m²Answer: 47 tiles | Buy 16.6 m² of tiles
💡 Order by m² not piece count -- tile packs list coverage in m². At 1.08 m² per pack (3 tiles), order 16 packs = 16.16 m², or 17 packs to be safe.
Standard
Shower recess -- mosaic tile diagonal
Given: Shower area: 2.1m x 1.8m = 3.78 m² | Tile: 100mm x 100mm mosaic | Waste: 15% diagonal
Working:
Tile area: 0.1 x 0.1 = 0.01 m² | Tiles net: 3.78/0.01 = 378 | With 15%: 378 x 1.15 = 434.7 -> 435 tiles | Area: 3.78 x 1.15 = 4.35 m²Answer: 435 tiles (100x100mm) | 4.35 m² to buy
💡 Mosaic tiles often come on sheets -- confirm sheet coverage before ordering. A 300x300mm sheet of 100mm mosaics covers 0.09 m² per sheet. Need: 4.35 / 0.09 = 49 sheets.
Advanced
Combined floor and wall area with different tiles
Given: Floor: 15.12 m² at 600x600 straight | Walls: 32 m² at 300x600 straight | Separate orders
Working:
Floor: 15.12 x 1.10 = 16.63 m² | Wall: 32 x 1.10 = 35.2 m² | Different tile sizes -- order separatelyAnswer: Floor: order 17 m² of 600x600 | Walls: order 36 m² of 300x600
💡 Always order floor and wall tiles separately -- different sizes, different waste factors, different laying sequences.
4 Sanity check
Waste allowance by pattern and complexity
Straight lay, simple room: 10% | Diagonal or feature: 15% | Complex shapes, multiple cuts: 20%
Always order by m² not piece count
Tiles come in packs/boxes -- list the m² requirement for the supplier to pack correctly
Order matching tiles from the same batch
Tile shade, size and surface texture vary between batches | Always order 10-15% extra from the same batch for future repairs
Check tile suitability for wet areas
Floor tiles: anti-slip rating R10 minimum for wet areas | Mosaic tiles: usually fine for wet areas
5 Common errors
| Error | Cause | Consequence | Fix |
|---|---|---|---|
| Not ordering extra tiles for future repairs from the same batch | Ordering only the quantity needed plus waste | Years later, a cracked tile cannot be matched because the batch is discontinued | Order an extra 5-10% beyond the waste calculation and store flat in a dry location. This tile repair insurance is far cheaper than trying to match tiles years later. |
| Not deducting areas that will not be tiled (bath, vanity footprint, built-in furniture) | Using the gross room area without deductions | Overordering by 5-20% on rooms with fixed fittings | Deduct the floor area under any built-in furniture, freestanding baths (if tiles will not go under), and permanent built-ins. For vanity units on legs, the floor under them is usually tiled -- only deduct fixed floor-mounted bases. |
| Using the same waste percentage for different room complexities | Applying 10% waste to every job | Running short on complex-shaped rooms or diagonal patterns | Increase waste to 15% for rooms with many internal angles, niches, diagonal laying and small or linear tile formats. Use 20% for highly complex feature work or micro-mosaic tiles. |
| Not checking tile batch numbers when ordering multiple packs | Ordering without specifying the same batch | Colour variation across the same installation -- highly visible in most tile formats | Specify that all packs must be from the same batch number. For large quantities, request the supplier to reserve full batch quantities before placing the order. |
6 Reference & regulatory links
7 Professional workflow
Common tools used alongside this one: