Wall Paint Calculator (Liters)

How to estimate wall paint in m²

The formula is liters = (area × coats) / yield. On top of that, add a 10% margin to cover roller losses, touch-ups and the spots that drink more paint than the rest. Acrylic latex on a smooth wall covers 12–14 m²/L per coat, so 13 is a safe number to plan around. Most jobs need 2–3 coats. Two will do for white-on-white or repainting the same color; go to three when you're changing colors or working over a porous surface. Say you have a 30 m² wall and want 3 coats at 13 m²/L: (30 × 3) / 13 = 6.9 L, which rounds up to a 7 L can (or 1× 3.6 L gallon + 1× 3.6 L gallon). The Brazilian standard NBR 15079 sorts water-based paints into premium, standard and economy tiers based on wash resistance, hiding power and yield, and the premium grade tends to earn its price back over the years.

Applications

Budgeting a home renovation, planning a commercial job (offices, retail, shared spaces), pricing a repaint at Leroy Merlin, C&C or Telhanorte, weighing the material cost of doing it yourself against hiring a painter, and double-checking a pro's quote so you don't get overcharged on materials.

FAQ

Why use 10% as the safety margin? It covers what the roller wastes, the drips, the odd extra coat a patch ends up needing, and any touch-ups down the line. Rooms with lots of cuts and corners are safer at 15%.

Do I count doors and windows? Subtract them from the gross area. Figure each interior door at about 1.6 m² and each window at about 2 m². If you're painting them too, count them on their own.

How many coats really? Two is the safe minimum. Bump it to three when you're going dark over light, painting fresh plaster, or covering a rough texture. A single coat almost always leaves blotches you can see.