A worked example with two coats and an assumed paint coverage gives roughly 7.32 litres including allowance.
Assumptions
A 4 × 3 m room has 2.60 m high walls, one 0.80 × 2.10 m door and one 1.20 × 1.20 m window. We assume two coats, 10 m² per litre per coat and a 10% allowance.
Wall area
Perimeter: (4 + 3) × 2 = 14 m. Gross wall area: 14 × 2.60 = 36.40 m².
Subtract openings
Door: 1.68 m². Window: 1.44 m². Net wall area: 36.40 − 1.68 − 1.44 = 33.28 m².
Estimate paint
Two coats cover 33.28 × 2 = 66.56 m². At the assumed coverage, 66.56 ÷ 10 = 6.656 L. With 10% allowance: 6.656 × 1.10 ≈ 7.32 L.
What to verify
Check the product coverage rate and whether the surface requires primer, sealing or extra coats. Package sizes affect what you will buy. This is a geometric example, not a guarantee of real consumption.
Result: approximately 7.32 L for these assumptions. Adjust all inputs in ParedExacta.
Try it in ParedExacta
Enter your own measurements and compare the result. Actual quantities depend on your materials.