Paint Calculator (litres needed)

How it works

Paint needed is the wall area times the number of coats, divided by the coverage of your paint. Coverage is printed on the tin, typically around 10–12 m² per litre per coat. So 40 m² in two coats at 10 m²/L takes 8 litres. Always plan two coats. A single coat rarely covers evenly, especially over a colour change or fresh plaster, and the second coat is what gives the depth and uniformity you actually want. Dark colours over light walls sometimes need three. To get the wall area, add up (length × height) for each wall, then subtract the doors and large windows — a standard door is roughly 2 m². Bare plaster, wood and porous surfaces drink far more paint on the first coat, so a primer is cheaper than an extra coat of finish. Buy a single large tin rather than several small ones: less cost per litre, and no batch-to-batch colour variation.