How Much Paint Do I Need?

Start with gross wall area — perimeter × wall height — then subtract standard openings: about 21 sq ft per door and 15 sq ft per window. Multiply the remaining net area by the number of coats you're applying, since a second coat roughly doubles the paint needed.

Most interior paints cover 300–400 sq ft per gallon on a smooth, primed wall; textured surfaces or unprimed drywall can reduce coverage significantly, so check your specific product's label rather than assuming the average.

The Paint Calculator handles the door/window subtraction and multi-coat math in one step.

Primer is a separate calculation from topcoat paint — this calculator estimates finish coats only. Add primer gallons on top using the same net wall area if the walls are unprimed drywall, or you're covering a dark color with a lighter one.