Free paint calculator: estimate how many liters or gallons of paint you need for any room. Input wall area, number of coats, and paint coverage. Prevent overbuying or running short.
Calculating paint quantity is about more than just wall area — it depends on how many coats you need, the surface texture, and the paint's coverage rate. This calculator uses the standard formula used by professional painters: multiply your wall area by the number of coats, then divide by the coverage rate your paint provides.
Enter the total wall area you want to paint, select the number of coats (two is standard), and adjust the coverage rate if you know your paint's specifications. The result gives you both liters and US gallons so you can buy the right amount regardless of where you shop. Add 10% to the result for very rough or unpainted surfaces.
Multiply the wall height by the wall width for each wall, then add them together. Don't subtract doors and windows unless they're very large — it's better to have a little extra paint than to run short. A standard 4m × 3m room with 2.5m ceilings has about 35 m² of wall area.
Two coats are recommended for most painting projects. One coat rarely provides even coverage, especially with color changes. Primer plus one topcoat is the industry minimum; primer plus two topcoats gives the best finish and durability.
Most emulsion paints cover 10–12 m² per liter on smooth surfaces. Rough or porous surfaces reduce coverage to 8–10 m²/L. Always check the manufacturer's label — the stated coverage is measured under ideal lab conditions and you should reduce it by 10% for real-world application.