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.
Bathroom tile calculator — frequently asked questions
How do I calculate bathroom tiles for walls and floor?
Calculate walls and floor separately. For each wall, multiply width × height then subtract any doors or windows. For the floor, multiply length × width. Add all areas together for your total. Always add 10–15% waste margin for cuts, breakages and future repairs. The calculator handles each surface individually and gives you a combined total.
Do bathroom walls and floors need different tiles?
Not necessarily, but wall tiles are often lighter and thinner than floor tiles. Floor tiles must have a slip resistance rating of P3 or better (to AS 4586) for wet area floors in Australian homes. Wall tiles don't have this requirement. Many homeowners choose one tile for both to simplify ordering and create a consistent look.
How much waterproofing do I need for a bathroom in Australia?
Under the NCC (National Construction Code), all shower recesses and bath surrounds must be waterproofed to AS 3740. Shower walls typically need waterproofing to 1.8 m high. The floor and 150 mm up the wall must be waterproofed in all wet areas. This is non-negotiable in Australia — skipping waterproofing is the number one cause of bathroom leaks and insurance claims.
What grout joint width should I use for bathroom tiles?
2–3 mm for rectified tiles (precision-cut with very consistent dimensions). 3–5 mm for standard wall tiles. 5–10 mm for floor tiles and larger format tiles. Narrower joints look cleaner but are harder to keep clean. Wider joints are more forgiving to lay and allow more movement between tiles.
How long does a bathroom tile job take in Australia?
A standard Australian bathroom (around 4–6 m²) takes a professional tiler 1–2 days to tile, not including waterproofing cure time (typically 24 hours before tiling) and grout cure time (24–48 hours before use). Full renovation including waterproofing, tiling, grouting and sealing typically takes 3–5 days from start to use.