Paint Coverage Calculator
Litres of paint from area, coverage, and coats.
Inputs
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Formula
litres = (area × coats ÷ coverage per L) × (1 + waste% / 100)
Multiply wall area by the number of coats, divide by the paint's stated coverage per litre, then add a waste allowance for roller absorption and touch-ups.
Worked example
40 m² with two coats at 12 m²/L needs 6.67 L base. With 10% waste, buy about 7.3 L — round up to the next tin size (often 4 L + 1 L, not 7 L exactly).
Where this can give the wrong answer
- Porous brick or new plaster drinks paint — effective coverage can drop 20–30% vs smooth drywall.
- Dark colour over light may need extra coats not in the default two.
- Ceiling area is included only if you add it to the surface area field.
FAQ
- Run the calculator separately for primer (often one coat, different coverage) and topcoat.