Paint Coverage Calculator — Australian Metric
Enter surface area
Enter the total area to be painted. For a full room, use the Room Paint Calculator to get this figure automatically.
Coverage rate is approximate and varies by brand. Check your product data sheet for the exact spread rate.
Paint required
This paint coverage calculator estimates the litres of paint required for any surface area, applying the coverage rate appropriate for the surface type. Australian paint products are rated in square metres per litre (m²/L) on their product data sheets — this calculator uses typical published spread rates: smooth surfaces 16 m²/L, standard rendered or brick surfaces 12 m²/L, rough or porous surfaces 8 m²/L, and highly porous substrates such as bare timber or fibre cement 6 m²/L. The tool is brand-neutral. Always confirm the specific spread rate on your chosen product's data sheet, as coverage varies between brands and formulations.
Frequently Asked Questions
What is a typical paint coverage rate in Australia?
Most interior wall paints sold in Australia cover 12–16 m² per litre on a smooth, previously painted surface at the recommended spread rate. Exterior paints and primers on rough or porous surfaces can drop to 6–10 m²/L. Always check the product data sheet — not the label — for the exact spread rate under your conditions.
How many coats of paint does a room need?
Two coats is standard for a quality finish on previously painted walls in reasonable condition. New plasterboard, bare plaster, or a significant colour change (especially going lighter) will require a sealer or primer plus two topcoats — effectively three coat layers. One coat may be sufficient for a same-colour refresh on a smooth, well-prepared surface.
Why does surface type affect how much paint I need?
Rough and porous surfaces have far more physical area to cover at a microscopic level and absorb more paint into the substrate. A bare brick wall can consume more than twice the paint of smooth plasterboard at the same nominal m² area. Priming porous surfaces before topcoating significantly reduces overall paint consumption.
What can sizes are available in Australia?
Australian paint is commonly sold in 500 mL, 1 L, 2 L, 4 L, 10 L and 15 L containers. Tinted paints are usually mixed in 1 L, 2 L, 4 L, and 10 L sizes. Buying in the largest can size that covers your job reduces cost per litre and minimises colour-match risk between batches.
Should I add extra for touch-ups?
Yes. A 10% buffer is sensible for touch-ups after the job is complete, particularly if you have feature walls, alcoves, or complex cut-in work. Keep a sealed leftover tin in a cool dark place for future touch-ups — label it with the room name, product name, and tint code.
How to use this calculator
- Enter the total area — input the total surface area in m². Measure length × width for each surface (walls, ceiling) and add them together. Deduct large door and window openings.
- Enter number of coats — most interior walls need 2 coats for good opacity; bare plaster or strongly contrasting colour changes may need 3. Ceilings typically need 2 coats.
- Select surface type — smooth (16 m²/L) for previously painted well-prepared surfaces; standard (12 m²/L) for typical interior walls; rough (8 m²/L) for texture-coated or porous surfaces; highly porous (6 m²/L) for bare plaster or unpainted masonry.
- Read the result — total litres required and a suggested tin purchase quantity rounding up to the nearest standard tin size.
Worked example: Painting three walls of a living room, total area 36 m², standard surface (previously painted), 2 coats. Coverage = 36 ÷ 12 × 2 = 6.0 L. Buy one 4 L tin and one additional 4 L tin. Or choose a 10 L tin if the ceiling is also being painted — a 10 L tin at $90–$110 is better value than two 4 L tins at $55–$65 each.
Understanding your results
The calculator returns total litres and a suggested tin purchase quantity, rounding up to the next available tin size (1 L, 4 L, 10 L). Coverage rates are based on Australian interior paint applied by roller at standard wet film thickness — as described on the Technical Data Sheet (TDS) for most Australian paint brands.
Coverage rates can vary significantly between products. Budget paints often have lower solids content and may achieve only 10 m²/L on standard surfaces. Premium paints (Dulux Wash & Wear Ultra, Taubmans EnduraWall) can achieve 14–16 m²/L. Always check the actual product TDS — available on each brand's website.
If changing from a dark colour to a light colour, or covering a strong feature wall, you may need 3 coats or a specialist primer/sealer first coat. An undercoat tinted to 50% of your final colour significantly reduces the number of finish coats required.
Common mistakes: Overloading the roller with too much paint (causes drips and reduces coverage), applying one very thick coat instead of two thin coats, and not stirring paint between coats (pigment settles to the bottom of the tin).
Paint coverage rates — what affects how far your paint goes
Understanding paint coverage is more nuanced than dividing area by the figure on the tin. Several real-world factors significantly affect how far your paint goes, and knowing them helps you buy the right amount and avoid costly extra trips back to the store.
Surface porosity
Raw, unsealed surfaces absorb dramatically more paint than previously painted ones. Bare plaster (new or after stripping) can absorb 30–50% more paint than the label suggests. Always seal bare plaster with a PVA sealer or diluted first coat before applying finish coats — this fills the surface pores and allows subsequent coats to achieve full coverage at normal rates. Bare render, brick, or masonry should also be sealed before painting.
Application method
Roller application achieves the coverage rates listed on most Australian paint products. Brush application uses slightly more paint due to brush loading. Airless spray can improve coverage by 10–15% on smooth surfaces, but requires skill — overspray and bounce waste must be factored in. If spraying, add 10–15% to your calculated quantity even with careful masking.
Colour and tinting
Deep base paints (used for dark colours) have lower pigment density than pastel bases — dark accent colours like charcoal, navy or forest green may require 3 coats for full opacity and typically have a lower stated coverage rate. White and off-white paints have the highest pigment loadings and achieve the best coverage.
Temperature and humidity
In hot Australian conditions, paint dries faster on the surface, making it harder to maintain a wet edge. This leads painters to overload rollers, reducing coverage and increasing the risk of runs and sags. Paint in the early morning or late afternoon in summer; never apply in temperatures above 35°C or below 10°C. High humidity in coastal or tropical areas can slow drying and affect film formation.
Tin sizes available in Australia
Standard Australian paint tin sizes are 1 L, 4 L, 10 L, and 15 L (trade/bulk). Some brands offer 2 L and 8 L sizes. Price per litre decreases significantly as tin size increases — a 10 L tin is typically 30–40% cheaper per litre than two 4 L tins covering the same area.
Australian standards and references
- AS/NZS 2311:2017 — Guide to the painting of buildings (coverage rates, surface preparation, and number of coats for different substrate types)
- AS/NZS 2310:2002 — Glossary of paint and painting terms
- AS 1580 — Methods of test for paints and related materials (including wet film thickness, dry film thickness and spreading rate)
- Master Painters Australia (MPA) — Technical guidance on coverage rates and application methods for residential painting in Australia
- Dulux, Taubmans, Haymes, Solver, Wattyl Technical Data Sheets — Manufacturer-specific spreading rates by product and surface type; always consult the specific TDS for the paint you are using