Choose one room unit
Select m, cm or mm. The choice applies to every area and exclusion, and existing entries are converted if you switch units.
Australian metric calculatorStart with your measurements
Tile calculator Australia
Use this tile estimator to calculate square metres, whole tiles, supplier boxes and optional material cost for floors or walls. Choose metres, centimetres or millimetres, add every section, subtract exclusions and select a waste allowance.
How many tiles do I need?
Measure the tiled area, subtract untiled sections, apply your chosen waste allowance, then divide by one tile's area and round up. Enter supplier box coverage to round up a box order as well.
✓ m, cm or mm inputs✓ Transparent formula✓ Whole-box rounding
How to use the tile calculator
From room measurements to an order estimate
Work through these four steps. You can use metres, centimetres or millimetres for rooms and exclusions; tile dimensions remain in millimetres, as commonly shown by suppliers.
Add all tiled sections
Measure length × width for each rectangular floor or wall. Add another area for L-shaped rooms or separate wall sections.
Subtract exclusions
Add doors, windows, islands or fixtures that will not be tiled. The calculator subtracts these from the gross measured area.
Enter tile and box details
Use the tile size and box coverage printed by the supplier, choose waste, then calculate. Confirm the final order with the supplier.
Tile planning answers
Common tile calculator questions
These answers explain the measurements and supplier details behind the estimate. The calculator still keeps your exact result and rounding visible.
How do I calculate square metres for tiles?
Multiply each rectangular section's length by width in metres, add the sections, then subtract untiled areas. This square metre tile calculator converts cm or mm room measurements to metres first. To estimate tiles per square metre, divide 1 m² by one tile's area.
How many 600 × 600 mm tiles cover 20 m²?
One tile covers 0.36 m², so 20 m² needs 56 whole tiles before waste. With a user-selected 10% allowance, 22 m² requires 62 whole tiles. Both results are rounded up.
How do I measure an L-shaped room?
Split it into non-overlapping rectangles and add each as a separate area. Measure every rectangle in the same selected unit so no part is counted twice.
How do I subtract doors, windows, islands or fixtures?
Add only rectangles that will not be tiled. For wall projects this may include doors or windows; for floors it may include a fixed island. Total exclusions must remain smaller than gross area.
What tile waste percentage should I use?
There is no universal tile waste allowance. Cuts, pattern, tile variation, breakage and future spares can change the amount. Select the value appropriate to your project and confirm it with your supplier or installer.
How are boxes of tiles calculated?
It divides required coverage by the square metres per box printed by the supplier, then rounds up. Box coverage is not inferred from tile dimensions because packaging varies by product.
Can I enter centimetres or millimetres?
Yes. Choose m, cm or mm for all room areas and exclusions; changing the unit preserves the represented size. Tile length and width are entered separately in millimetres.
What does the estimate include for grout, adhesive, labour and delivery?
Optional cost is only whole boxes multiplied by your entered box price. It excludes labour, delivery, grout, adhesive, trim, substrate work and other installation or compliance costs.
Methodology
How the tile estimate is calculated
Room inputs are normalised to metres, the calculator keeps full precision during calculation, displays areas to two decimal places and always rounds tile and box quantities up to whole units.
Measure gross area
Add the length × width of every rectangular area.
gross area = Σ(length × width)Subtract exclusions
Remove doors, windows, fixtures or other untiled rectangles.
net area = gross area − exclusionsAdd your waste allowance
Apply the percentage selected for cuts, breakage and spares.
required area = net area × (1 + waste ÷ 100)Calculate one tile's area
Convert both tile dimensions from millimetres to metres.
tile area = (tile length mm ÷ 1,000) × (tile width mm ÷ 1,000)Calculate whole tiles
Divide required coverage by one tile's area and round up.
tiles required = ceiling(required area ÷ tile area)Calculate supplier boxes
Use the coverage printed on the box, then round up.
boxes required = ceiling(required area ÷ supplier box coverage)Verified examples
Regression-tested calculations
These fixed cases are checked by the automated formula test suite so rounding and unit conversion changes cannot pass unnoticed.
| Scenario | Key inputs | Verified result |
|---|---|---|
| Single 20 m² room | 10% waste; 600 × 600 mm | 62 tiles, 16 boxes and $1,280 using 1.44 m²/box at $80 |
| Multiple areas and an exclusion | 6 m² + 3 m² − 2 m²; 15% waste; 300 × 600 mm | 7 m² net, 8.05 m² required, 45 tiles, 6 boxes |
| Unit equivalence | 4 m × 5 m, 400 cm × 500 cm or 4,000 mm × 5,000 mm | The same 20 m² gross area and order estimate |
| Exact box boundary and round-up boundary | 2.88 m² or 2.8801 m² required | 2 boxes or 3 boxes respectively, using 1.44 m²/box |
| Non-divisible tile size | 1 m²; 333 × 333 mm tiles; 0% waste | 10 whole tiles after rounding up |
Worked example
A 4 m × 5 m room with 600 mm tiles
A 20 m² room with 10% waste needs 22 m² of coverage. With 600 × 600 mm tiles and 1.44 m² per box, the estimate is 62 tiles or 16 boxes. At $80 per box, the material estimate is $1,280.
- Net area
- 20.00 m²
- With 10% waste
- 22.00 m²
- Order
- 16 boxes
What this estimate includes
- Rectangular floors and wall sections
- Rectangular exclusions
- Your selected waste allowance
- Supplier-stated box coverage and price
What it does not include
- Grout, adhesive or trim quantities
- Labour, delivery or installation quotes
- Substrate or structural advice
- Pattern-specific professional set-out
Sources and review record
| Calculation rule | Supporting source | Formula version | Checked date |
|---|---|---|---|
| Area, waste and box-coverage inputs | National Tiles | 1.1 | |
| Exclusions, whole tiles and optional cost | Show Tile | 1.1 | |
| Tile dimensions in millimetres | Johnson Tiles | 1.1 | |
| Equations, rounding and expected results | Formula specification v1.1 and automated acceptance tests | 1.1 |
Recheck quarterly and whenever a source, formula, rounding rule or supplier convention changes. Version 1.1 adds equivalent m, cm and mm conversion without changing the ordering method.