Paint coverage calculator
Work out how many litres of paint to buy for a wall, ceiling or room, based on the area, number of coats and your paint's stated coverage.
Result
Paint required
How to use this tool
- Measure the total area you're painting.
- Check the coverage figure on your paint tin or manufacturer's product data and enter it; the default is illustrative.
- Enter how many coats you're applying.
- Read the litres required.
Assumptions
- Area × coats is the planned surface area to cover; the resulting litres are an estimate because actual coverage depends on paint, surface and application. The editable 12m²/L default is illustrative, not a product yield.
- No allowance is added for spillage, priming or a second colour test patch. Use the tin or manufacturer data for the chosen product and surface.
Technical details: what the fields mean
- Area to paint
areaM2 - Total surface area to paint, in square metres.
- Number of coats
coats - Number of coats in your planned application; follow the product instructions for preparation and coats.
- Coverage per litre (check your paint tin)
coveragePerLitreM2 - How many square metres one litre covers per coat. This varies significantly by paint brand and surface porosity — always check the tin.
Methodology
Litres = (area × coats) ÷ coverage per litre.
Worked example
20m² wall, 2 coats, 12m²/L coverage
Inputs: Area to paint: 20 m², Number of coats: 2, Coverage per litre (check your paint tin): 12 m²/L
Result: 3.3 litres required
Practical guidance
- Round up to the next full tin size — leftover paint is useful for touch-ups.
- Bare plaster and new woodwork often need a mist coat / primer first, which uses more paint than the topcoats.
Common mistakes
- Using the default coverage figure instead of the one printed on your actual tin.
- Forgetting that a mist coat on new plaster covers less area per litre than a standard coat.
FAQs
How much paint do I need for a 20m² wall?
With 2 coats at 12m²/L coverage, about 3.3 litres — but check your specific paint's coverage first.
Why does my paint tin's coverage figure matter so much?
Coverage depends on the specific paint and surface. Use the figure and application guidance published for the product rather than relying on this illustrative default.
Last reviewed: 2026-10-11
Coverage is manufacturer- and surface-dependent — treat this as a purchasing estimate, not an exact figure.
This tool provides an indicative estimate, based on the assumptions stated above.
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