Paint Calculator – Litres of Paint for Room and Wall
Calculate exactly how many litres of paint you need for any room. Automatically deducts door and window areas.
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Paint Calculation Formula
Wall Area = 2 × (L + W) × H Deductions: Door = 1.8 m² | Window = 1.2 m² Paint Litres = Net Area × Coats / Coverage (12 m²/L)
Room 5×4m, 3m high, 1 door, 2 windows, 2 coats: Wall Area = 2×(5+4)×3 = 54 m² Net = 54 − 1.8 − 2.4 = 49.8 m² Paint = 49.8 × 2 / 12 ≈ 9 litres
Frequently Asked Questions
On average, 1 litre of paint covers approximately 10–12 square metres per coat on a smooth wall surface. Rough or porous surfaces may reduce coverage to 8–10 m² per litre.
For new walls, 1 coat of primer followed by 2 coats of finish paint is recommended. For repainting over an existing colour, 2 coats are usually sufficient.