Construction & Trade
Paint Calculator
Calculate litres of paint needed for a room based on wall dimensions, coats, and exclusions for doors and windows.
How this calculator works
Calculates total wall area (perimeter x height), subtracts door (1.8m²) and window (1.5m²) areas, optionally adds ceiling area (length x width), multiplies by number of coats, then divides by coverage rate to get litres needed. Rounds up to practical tin sizes.
Standard Australian ceiling height is 2.4m or 2.7m
2 coats is standard. Dark colours over light may need 3.
Typical wall paint covers 10-14 m² per litre
Dulux Wash & Wear is ~$15/L in 15L buckets
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FAQ
Frequently asked questions
How much paint per square metre?
Standard wall paint covers 10-14 m² per litre for one coat, depending on surface texture and paint quality. Rough surfaces and porous plaster need more paint. Always check the specific product's coverage rate on the tin.
How much does a room cost to paint in Australia?
DIY paint for a standard bedroom (4x3m) costs about $100-$200 in materials (paint, tape, drop sheets). Professional painters charge $250-$600 per room depending on preparation, size, and location.
Do I need primer?
Primer is recommended for new plasterboard, bare timber, stained surfaces, and when making a dramatic colour change. Self-priming paints (like Dulux Wash & Wear) can skip primer on previously painted surfaces in good condition.
What size tins should I buy?
Paint is available in 1L, 2L, 4L, 10L, and 15L. The best value per litre is 10L or 15L tins. Buy the smallest size that covers your needs to avoid waste, but round up — leftover paint is useful for touch-ups.
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