Paint Coverage Calculator – How Far Does a Litre of Paint Go?
Not sure what coverage rate to use? Our calculator applies the right coverage rate for your surface type automatically — and shows you exactly how much paint to buy.
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What Is Paint Coverage?
Paint coverage (also called spreading rate) is the area that one litre of paint covers in a single coat, expressed as m² per litre (m²/L). Standard interior latex paint covers 10–12 m²/L on smooth surfaces. Understanding coverage rate is the foundation of any accurate paint calculation.
Coverage rates vary significantly by product quality, surface type, and application method. Always check the spreading rate on your specific paint tin — and use a lower rate for rough or porous surfaces.
Paint Coverage Rates by Surface Type
| Surface | Coverage per Litre | Notes |
|---|---|---|
| Smooth interior drywall | 10–12 m²/L | Standard coverage |
| New / bare drywall | 8–10 m²/L | More porous, prime first |
| Previously painted smooth wall | 10–13 m²/L | Best coverage |
| Textured walls | 7–9 m²/L | More surface area |
| New plaster | 8–10 m²/L | Seal before painting |
| Timber / wood | 8–10 m²/L | Sand smooth first |
| Masonry / brick | 5–7 m²/L | Very porous |
| Exterior render (smooth) | 8–10 m²/L | Use exterior grade |
| Exterior render (rough) | 4–7 m²/L | High absorption |
| Metal (primed) | 12–14 m²/L | Smooth surface |
| Ceiling paint (flat) | 10–12 m²/L | Usually 1 coat |
Factors That Reduce Paint Coverage
Surface Texture
Heavily textured surfaces have more total surface area than flat ones. Rough render, brick, and popcorn ceilings can reduce effective coverage by 20–40%.
Porosity
New plaster, bare timber, and unprimed drywall are very porous. They soak up paint heavily on the first coat — this is why primer is essential on new surfaces.
Colour Change
Going from a dark colour to a lighter one is one of the hardest repaints. Expect 3 or more coats, or use a specialist tinted primer to block the old colour.
Application Method
Sprayers apply paint very evenly but require thinning (which reduces coverage). Rollers are most efficient. Brushes are least efficient on large areas due to variable thickness.
Coverage Tips
Never use the maximum listed coverage rate — real-world conditions always reduce it
Test a small area first when switching to a new paint brand or product
Prime porous surfaces — this seals the substrate and dramatically improves topcoat coverage
Apply two thin coats rather than one thick coat for more consistent coverage
Don't overwork wet paint — this stretches thin areas and causes uneven coverage
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