How this calculator works
Each surface (floor and walls) is calculated separately, then combined. The formula for each: surface area (m²) ÷ tile area (m²) × waste factor = tiles needed. Openings (doors, windows, niches) are subtracted from wall area before the tile count is run.
Waste factors by lay pattern: straight lay 10%, brick bond 10%, diagonal 15%, herringbone 20%. Wall tiling generally uses the same waste margins as floor tiling — the cuts at edges, corners and around fixtures are just as numerous.
Popular Australian bathroom tile sizes
- 600 × 600 mm — the most popular bathroom tile in AU right now. Large format, fewer grout lines, clean modern look. Works on both floors and walls.
- 600 × 300 mm — the standard "plank" wall tile. Classic, versatile, suits almost every bathroom style.
- 300 × 600 mm — the subway-style option. Used vertically or horizontally, suits both contemporary and Hamptons aesthetics.
- 600 × 1200 mm — the slab format seen all over The Block. Dramatic look, very few grout lines. Higher cutting waste, requires an experienced tiler to lay correctly.
- 75 × 300 mm / 100 × 200 mm — small subway tiles. Classic, timeless. Used heavily on splashbacks and feature walls.
- 300 × 300 mm — still common in older-style bathrooms and wet areas. Easy to lay, economical, good for shower floors with slight fall.
Wall vs floor tiles — are they the same?
Not always, and this matters when buying:
- Floor tiles must have a slip rating (P3 minimum for wet areas in Australia under AS 4586). Wall tiles don't need a slip rating.
- Wall tiles are often thinner and lighter — easier to handle when tiling vertically.
- Many modern large format porcelain tiles (600×600, 600×1200) are rated for both floors and walls — check the tile's data sheet before buying.
- Mosaic and glass tiles — walls and splashbacks only, never floors.
Grout and adhesive
For budgeting purposes:
- Grout: approximately 1.5–2 kg per m² for standard tiles with 2–3 mm joints. For larger format tiles with thin joints (1 mm), allow about 0.5–1 kg per m².
- Tile adhesive: approximately 4–5 kg per m² with a 10 mm notched trowel for wall tiles. Floor adhesive (with back-buttering) uses 5–6 kg per m².
- Both come in 15 kg and 20 kg bags. Your tile supplier will confirm exact quantities for your chosen product.
The Block tile rules worth knowing
If you're planning a bathroom reno after watching The Block, a few practical points:
- Large format tiles need a flat substrate. 600×1200 tiles require the wall or floor to be within 3 mm flat in any 3 m span. Older homes rarely meet this without prep work.
- Order from the same batch. Tile colour and shade vary between batches (dye lots). Always order enough in one go — matching batches later is unreliable.
- Shower recesses need waterproofing first. AS 3740 requires two coats of waterproofing membrane on all shower walls before tiling. Budget for this — it's not optional.
- Feature tiles use more waste. If you're mixing a feature tile with a standard tile, calculate each area separately and add 15% waste for the feature tile.