Tile Calculator Australia — Quantity, Wastage & Area
Enter area and tile details
Typical: rectified tiles 1.5–3 mm · standard tiles 3–5 mm · natural stone 5–10 mm
Tiles to order
This tile calculator works out how many tiles to order for any floor or wall area, accounting for tile size, grout joint width, lay pattern, and an Australian-standard wastage allowance. Tile sizes are entered in millimetres as marked on Australian product packaging. Wastage varies by lay pattern: straight grid requires a minimum 10% buffer; a 50% brick offset or diagonal pattern should carry 15–20% due to increased edge cuts. Always order from the same batch number to ensure colour consistency — Australian tilers recommend purchasing all tiles for a job in one order and returning any unopened boxes rather than under-ordering and re-purchasing from a different dye lot.
Frequently Asked Questions
How much wastage should I allow for tiling in Australia?
The Australian tile industry standard is 10–15% wastage for a straightforward square room with a straight lay pattern. Increase to 15–20% for diagonal, herringbone, or brick-offset patterns, and for rooms with lots of cut-outs (toilets, vanities, kitchen islands). Never order exactly the calculated amount — you'll almost always need extras for cuts and breakage.
What is a rectified tile and how does it affect grout joint size?
Rectified tiles are mechanically cut to exact dimensions after firing, giving a precision edge. They can be laid with a very narrow grout joint of 1.5–3 mm. Standard pressed tiles have dimensional variation of ±0.5–1 mm and need a minimum 3–5 mm joint to accommodate this. Using too-narrow a joint on non-rectified tiles causes lippage (uneven edges between tiles).
Does lay pattern affect how many tiles I need?
Yes. A diagonal (45°) lay increases tile consumption by approximately 15% because every edge tile must be cut at an angle, wasting more of each tile. A brick-offset (50% stagger) adds around 10% wastage compared to a straight grid. The calculator adjusts the wastage recommendation based on the pattern you select.
Why is it important to order from the same batch number?
Ceramic and porcelain tiles are fired in batches. Even the same product code can vary slightly in shade and calibre (dimensional size) between production batches. Mixing batches in the same area creates visible colour variation that cannot be fixed after grouting. Always check that all boxes share the same batch or lot number before purchase.
Can I use this calculator for wall tiles as well as floor tiles?
Yes. The calculation method is the same for floor and wall tiles. For wall tiles, measure the total wall area in square metres (height × width of each wall section) and deduct any openings such as windows, doors, or large fixtures before entering the total into the calculator.
How to use this calculator
- Enter the area — type the total surface area in m², or enter room length and width in metres and let the calculator multiply them.
- Enter tile dimensions — input tile width and height in millimetres as stamped on the box (e.g. 600 × 300 mm). Enter the same value for both if tiles are square.
- Set the grout joint — rectified tiles typically use a 2–3 mm joint; handmade or terracotta tiles need 5–10 mm. Check the tile manufacturer's recommendation.
- Choose your lay pattern — straight grid uses the fewest tiles; a 45° diagonal or herringbone adds 10–15% extra waste from cuts.
- Select wastage percentage — use 10% for a simple rectangular room, 15% for rooms with alcoves or angles, and 20% for diagonal lays or intricate patterns.
- Read the result — total tile count including your wastage allowance. Always buy in full box quantities to match batch numbers.
Worked example: Bathroom floor 2.4 m × 1.8 m = 4.32 m², using 600 × 300 mm tiles, 3 mm grout joints, straight lay, 10% wastage. Net tile count ≈ 25.2; with wastage = 28 tiles. Tiles come in boxes of 6, so order 5 boxes (30 tiles). Confirm box quantities with your tile store before purchasing.
Understanding your results
The calculator returns a tile count already including your chosen wastage allowance. This accounts for cuts at edges and unavoidable breakage during installation, but does not cover pattern matching for feature tiles (e.g. timber-look planks with a repeat) — add another 5–10% if pattern matching is required.
Always round up to the nearest full box. Running short mid-job is a real problem: tiles from different batches (shade lots) can vary slightly in colour and glaze even when the product code is identical. Buy all tiles from the same batch number, printed on the box label.
Keep 5–10% of offcuts stored flat in a dry location after the job. If a tile cracks or chips years later, having a matching batch spare is invaluable — discontinued colours are very difficult to source retrospectively in Australia.
Common mistakes: Forgetting to account for the grout joint (reduces effective coverage), measuring in centimetres instead of millimetres, and ordering in tiles rather than boxes. Check whether your supplier's minimum order is a full box or a half-box.
Tiling guide for Australian homes
Tiling is one of the most common trade and DIY tasks across Australia. Whether you're retiling a bathroom, laying a kitchen splashback, or covering an alfresco floor, getting your tile quantities right before you buy avoids costly delays and colour-lot mismatches.
Choosing the right tile for the application
Not all tiles are suitable for all applications. The key rating is the Porcelain Enamel Institute (PEI) wear rating for floor tiles: PEI 1–2 for walls and very light foot traffic only; PEI 3 for residential floors; PEI 4–5 for commercial and heavy-traffic areas. Wet areas (bathrooms, laundries, pool surrounds) require a minimum R10 slip resistance rating for floors — check the tile's technical data sheet.
Substrate preparation
In Australia's climate, substrate movement is a major cause of tile cracking. Concrete slabs should be cured for at least 28 days before tiling. Fibre cement sheet (Villaboard, Hardiflex) is the preferred substrate for wet areas on timber-framed walls — standard plasterboard is not suitable without a waterproofing membrane. Waterproofing to AS 3740 is mandatory for all wet areas before tiling commences.
Adhesive and grout selection
Use a polymer-modified tile adhesive for all floor and wet-area applications. Large-format tiles (600 mm+) require a flexible adhesive — check the adhesive's maximum open time, as large tiles take longer to position. Epoxy grout is recommended for kitchens; cement-based grout in a matching colour is standard for most applications. Always seal cement-based grout within 48 hours of completion.
Alfresco and outdoor tiling
Outdoor tiles in Australia face significant thermal expansion from direct sun. Expansion joints must be incorporated at maximum 4.5 m centres in both directions and at all changes of plane — failure to include them is the leading cause of outdoor tile failure. Porcelain tiles rated R11 or above are recommended for outdoor areas to reduce slip risk in wet conditions.
Australian standards and references
- AS 3958.1:2007 — Guide to the installation of ceramic tiles (adhesive bed method)
- AS 3958.2:1992 — Guide to the selection of a ceramic tiling system
- AS 3740:2021 — Waterproofing of domestic wet areas (mandatory before tiling wet areas)
- AS 4586:2013 — Slip resistance classification of new pedestrian surface materials (R rating system)
- NCC Volume Two — Wet area waterproofing requirements for residential construction
- Tile Council of Australia (TCA) — Technical guidelines for tile installation, substrate preparation and grout joint sizing
- NATSPEC — Tiling specification clauses for commercial and residential construction