Ordering too few tiles is one of the most expensive mistakes in a renovation — particularly if the tile is discontinued or comes from a batch with a different shade number. Ordering significantly too many wastes money. Getting the calculation right before you place the order saves both.
This guide gives you the formula, the worked examples for different room types, and the wastage rates to apply for different laying patterns. For a room with complex shapes, multiple surfaces, or unusual features, book a design consultation at Iconic Tiles — we’ll help you quantify your order accurately.
🔲 Find Your Tiles First, Then Calculate Browse Iconic Tiles’ full range of bathroom floor tiles, wall tiles, and mosaic feature tiles — then use this guide to calculate your order. |
The Core Formula
The base calculation for any tile order follows this sequence:
- Calculate the total area to be tiled (in square metres)
- Add a wastage percentage appropriate to the laying pattern and room complexity
- Divide by the tile coverage per box to get the number of boxes required
- Round up to the nearest full box
| Step | Formula | Example |
| Area (m²) | Length (m) × Width (m) | 3.5m × 2.2m = 7.7m² |
| Add wastage | Area × (1 + Wastage %) | 7.7 × 1.10 = 8.47m² (10% added) |
| Tiles per m² | 1 ÷ (Tile Length m × Tile Width m) | 1 ÷ (0.6 × 0.6) = 2.78 tiles/m² |
| Total tiles needed | Area with wastage × Tiles per m² | 8.47 × 2.78 = 23.5 → 24 tiles |
| Boxes needed | Total tiles ÷ Tiles per box (round up) | 24 ÷ 6 = 4 boxes (if 6 per box) |
Note: most tile product listings specify coverage per box in m² — use this directly rather than calculating individual tile count if available.
Step 1: Calculate the Total Area
For a simple rectangular room, this is straightforward:
Area = Length × Width
For example: a bathroom floor 3.5m long and 2.2m wide = 7.7m²
For a rectangular wall: measure the height from floor to the top of the tiled area × the wall width. Deduct any windows or fixtures from the total, but be conservative with deductions — it’s better to overorder slightly than to underorder.
Rooms that aren’t simple rectangles
For L-shaped rooms, rooms with alcoves, or rooms with unusual angles, break the space into rectangular sections and calculate each separately, then add:
- Section A (main bathroom floor): 3.0m × 2.0m = 6.0m²
- Section B (toilet alcove): 1.0m × 1.2m = 1.2m²
- Total: 7.2m²
For shower recesses and niches, measure them separately — if they use a different tile or a mosaic insert, they need their own calculation.
| 💡 Measure twice: Measure your room dimensions in at least two places per wall — older Sydney homes in particular often have walls that aren’t perfectly parallel. Use the longest dimension for each wall measurement to avoid underordering. |
Step 2: Wastage Percentage — This Is Where Most Mistakes Happen
The standard industry recommendation is to add 10% to your tile order as a wastage allowance. This covers cuts, breakages during transport and installation, and future repair needs. However, the appropriate wastage percentage varies by the laying pattern chosen:
| Laying Pattern | Recommended Wastage | Why |
| Straight lay (grid pattern) | 10% | Minimal cuts — most efficient use of material |
| Offset / brick pattern | 10–12% | Offset cuts add modest additional waste |
| Diagonal (45° angle) | 15–20% | Diagonal cuts produce significantly more waste at edges |
| Herringbone | 15–20% | Complex pattern requires many cuts — high waste rate |
| Complex or irregular room shape | +5–10% extra | More cuts at multiple angles — apply additional buffer |
For mosaic tiles (sheets), the calculation is similar but use the sheet as your unit. Mosaic sheets typically have a specified coverage per sheet (e.g. 0.09m² per sheet) — divide your area by the sheet coverage, add 10% wastage, and round up.
Step 3: Wall Tile Calculations — Account for Fixtures
Bathroom wall tiles require measuring each wall section separately. The general approach:
- Measure the full wall area (height × width) for each wall to be tiled
- Deduct fixtures: doorways (deduct the opening), windows (deduct the glass area, not the full frame), large fixed mirrors if tiling behind them
- Don’t deduct smaller fixtures (towel rails, toilet roll holders, showerheads) — these are too small to meaningfully reduce tile area and the tiles around them need to be cut anyway
- Add all wall areas together and apply 10% wastage
| 📌 Shade lot matching: If you are ordering tiles in multiple deliveries or need to reorder, always specify the original shade lot number. Tiles from different production batches can have subtle colour differences invisible on individual tiles but visible side-by-side in a finished room. Check Iconic Tiles delivery information at iconictiles.com.au/delivery-info/ for order and reorder guidance. |
Worked Example: A Complete Bathroom
Here’s a full worked example for a typical Sydney ensuite:
| Surface | Dimensions | Area | After 10% Wastage |
| Floor | 2.4m × 1.8m | 4.32m² | 4.75m² |
| Shower floor | 0.9m × 0.9m (mosaic) | 0.81m² | 0.89m² |
| Wall 1 (main) | 2.4m × 2.4m (2.4m high) | 5.76m² | 6.34m² |
| Wall 2 (shower) | 0.9m × 2.4m (three sides = 5.4m²) | 5.4m² | 5.94m² |
| Wall 3 (vanity) | 1.2m × 0.6m (splashback only) | 0.72m² | 0.79m² |
| Total | — | 17.01m² | 18.71m² |
This bathroom would require approximately 18.71m² of tile — likely rounded to 19–20m² depending on box coverage sizes available for the chosen tile.
How to Convert m² to Boxes
Every tile product listing specifies either the number of tiles per box or the coverage in m² per box. Use m² per box coverage directly:
Boxes needed = Total m² (with wastage) ÷ m² per box → ALWAYS round UP to the nearest whole box
Example: 18.71m² ÷ 1.44m² per box = 12.99 → 13 boxes ordered
| 💡 Order a spare box: For large renovation projects, order one extra box beyond the calculated requirement and store it. If a tile needs replacing in five years, having a tile from the same shade lot available is invaluable — and the cost of one extra box is trivial compared to the cost of a visible patch repair with a slightly different tile. |
Quick Reference Wastage Rates
| Tile Type | Laying Pattern | Wastage to Add |
| Large format floor tiles | Straight lay | 10% |
| Large format floor tiles | Offset (brick) | 12% |
| Wall tiles | Straight or offset lay | 10% |
| Any tile | Diagonal | 15–20% |
| Any tile | Herringbone | 15–20% |
| Mosaic sheets | Any | 10% |
| Any tile | Complex or irregular room | Add extra 5–10% on top of above |
Order Your Tiles from Iconic Tiles Fast delivery 2–4 business days. Quality bathroom tiles, floor tiles, wall tiles, and mosaic features. Sydney’s tile specialists. |
Frequently Asked Questions
Underordering is a common and frustrating problem. If the tile is still in stock at Iconic Tiles, a second order is straightforward — but check delivery timing to ensure your tiler isn’t delayed. If the tile is discontinued or the production batch has changed, you may not be able to find an exact match. Always order with adequate wastage built in and save any leftover tiles for future repairs.
Calculate your room area in metres (m²) for clarity — most tile product listings specify coverage in m² per box. If working with tile dimensions in millimetres (e.g. 600×600mm), convert to metres first (0.6m × 0.6m = 0.36m² per tile) before calculating.
For practical purposes, the standard tile quantity formula (area ÷ tile size) produces accurate results without separately accounting for grout joints — the small amount of area occupied by grout is already effectively absorbed into the 10% wastage calculation. For precision ordering on very large areas, ask the team at Iconic Tiles to confirm the calculation. See the FAQ page for additional ordering guidance.
Yes — book a design appointment at Iconic Tiles Sydney and bring your room measurements. We’ll help you confirm the tile quantities needed for your specific tiles and layout, so you order correctly the first time.
