How much interior paint do you need for your walls?

Wall area is not floor area: a 4×5 m room with 2.7 m ceilings has roughly 54 m² of wall minus doors and windows — often 40–45 m² paintable. At 10 m²/L and two coats on a normal wall: about 8–9 liters before waste.

Two coats for any real color change or on new plaster. One coat is only realistic for maintenance when the existing paint is sound and you match the color. Dark-to-light jumps almost always need a primer coat too — the calculator assumes product coats only.

Ceiling paints are thicker and splatter less; coverage can be similar but application is slower. Add ceiling m² to your total area the same way — many people use the same calculator entry and buy a dedicated ceiling white.

10% is fine for rectangular rooms with a roller. Irregular shapes, lots of corners, or spraying push 15%. Buying an extra small can (0.75 L) for touch-ups is cheaper than a third trip to the store.