Estimate paint before buying
For a rectangular room, wall area is 2 × (length + width) × height minus openings. The ceiling is excluded. Use the product’s coverage per liter, coats, allowance and can size.
Example and limitations
A 5 × 4 m room, 3 m high, with 4 m² of openings has 50 m² of walls. Two coats at 10 m²/L need 10 L before allowance. Surface condition and paint type affect actual consumption.