How to calculate paint for an Australian room
The formula is: paintable area ÷ coverage rate × number of coats = litres needed. For a full room, paintable area is wall area + ceiling area, minus doors and windows. This calculator does all of that automatically.
How much does a litre of paint cover?
Most Australian paints cover 12–16 m² per litre per coat. Budget and trade paints typically sit at 12 m²/L. Mid-range paints (Dulux Wash&Wear, Taubmans, British Paints) are around 14 m²/L. Premium high-hide formulas can reach 16 m²/L. Always check the coverage rate on the tin — it varies significantly between products.
How many coats do I need?
- 1 coat — touch-up or same colour refresh over a sound surface
- 2 coats — standard for most repaints and new plasterboard
- 3 coats — dark colours, going light over dark, or heavily patched walls
New plasterboard always needs a sealer coat first — factor this in separately at 10–12 m²/L.
Walls vs ceiling — do I use the same paint?
Generally no. Ceiling paint is flat/matte to hide imperfections and reduce glare. Wall paint is usually low-sheen or semi-gloss for washability. Budget them separately — most painters apply ceiling white first, then cut in and roll the walls.
What tin sizes are available in Australia?
Standard sizes are 1 L, 2 L, 4 L, 10 L and 15 L. The 10 L tin is the best value for rooms over ~25 m² of paintable area. For small rooms or feature walls, 4 L is usually sufficient. Always buy slightly more than calculated — leftover paint is useful for touch-ups.
Paint calculator — frequently asked questions
How much paint do I need per square metre?
Most Australian interior paints cover 12–16 m² per litre for a single coat on a smooth, previously painted surface. On new plaster or bare surfaces, coverage drops to 8–10 m² per litre as the surface absorbs more paint. The calculator uses 12 m² per litre as a conservative default and adjusts for the number of coats you select.
How do I calculate how much paint I need for a room?
Add up all the wall areas (length × height for each wall), subtract doors and windows, then divide by the coverage rate of your paint. Don't forget to add the ceiling separately if you're painting it too. The calculator handles all of this — just enter your room dimensions and it does the rest.
How many coats of paint do I need?
Two coats is standard for most interior paint jobs in Australia. New plaster or a significant colour change (especially going lighter over a dark colour) may need three coats for full coverage. One coat is only sufficient for touch-ups or recoating the same colour.
What is the difference between interior and exterior paint in Australia?
Exterior paints are formulated to handle UV exposure, moisture and temperature swings — they're more flexible and mould-resistant than interior paints. Interior paints are designed for washability and low VOC in enclosed spaces. Never use interior paint outside; it will chalk, peel and fade quickly in Australian conditions.
How much does paint cost per litre in Australia?
Budget interior paint starts around $10–$15 per litre. Mid-range paints like Taubmans or Dulux Wash & Wear run $20–$30 per litre. Premium paints like Dulux Weathershield or Haymes sit at $35–$50+ per litre. Buying in 10 or 15 litre tins rather than 4 litre tins significantly reduces the per-litre cost on larger jobs.
Do I need to prime before painting in Australia?
Yes on bare plaster, new plasterboard, repaired surfaces and any surface where you're making a big colour change. Primer seals the surface, improves paint adhesion and gives you a more even topcoat — which ultimately means you need fewer topcoats to achieve full coverage.