Room Paint Calculator Australia — Walls, Ceiling & Deductions
Room dimensions
Standard door ≈ 2.0 × 0.9 m · Standard window ≈ 1.2 × 1.0 m
Paint required
This room paint calculator works out the exact litres of paint needed for an Australian room by calculating total wall area, adding the ceiling if required, then deducting the area of any doors and windows. Room dimensions are entered in metres — the standard used by Australian builders and painters. Coverage rates reflect typical Australian interior paint products: 16 m²/L on smooth plasterboard, 12 m²/L on rendered or medium-texture walls, and 8 m²/L on rough or porous surfaces. The tool is brand-neutral — confirm the spread rate on your specific product's data sheet before ordering. Always buy in the largest available can size to minimise cost per litre and reduce colour-match risk.
Frequently Asked Questions
Should I use the same paint for walls and ceiling?
Not usually. Ceiling paint is typically flat or low-sheen white, formulated to hide roller lines on horizontal surfaces. Wall paint is available in flat, low-sheen, semi-gloss, and gloss finishes depending on the room type. Most Australian painters use a separate ceiling white and a wall paint in the chosen colour and sheen level. Both quantities can be calculated using this tool by running it separately for ceiling and walls.
Do I need to deduct doors and windows from my paint calculation?
Yes, for accuracy. A standard 2040 × 820 mm door accounts for about 1.7 m², and a typical 1200 × 1000 mm window is 1.2 m². On a small room these deductions can represent 10–15% of the total wall area. This calculator lets you add as many openings as needed to get an accurate net paintable area.
How many coats does new plasterboard need in Australia?
New plasterboard (also called plaster, gyprock, or drywall) is highly porous and typically requires a sealer or primer coat before two topcoats — three coat layers in total. Skipping the sealer leads to uneven sheen and excessive paint consumption. Some premium paints marketed as "paint and prime in one" can reduce this to two coats on new plasterboard — check the product data sheet.
What paint sheen is right for different rooms?
In Australian residential practice: flat or low-sheen for living rooms and bedrooms; low-sheen or semi-gloss for kitchens and bathrooms (easier to wipe clean); semi-gloss or gloss for trims, architraves, and doors. High-humidity areas like bathrooms should use a mould-resistant formula. Gloss finishes highlight surface imperfections, so wall preparation is more critical.
How do I calculate paint for a room with a feature wall?
Calculate the feature wall separately using the Paint Coverage Calculator with the feature wall area, then use this room calculator for the remaining three walls with doors and windows deducted as usual. This gives you accurate quantities for each colour without mixing them into a single estimate.