Paint Calculator

About 350 to 400 square feet per coat on smooth, primed walls, according to Sherwin-Williams. Rough or porous surfaces such as textured drywall, stucco or bare wood soak up more, so expect 200–300 sq ft. The exact figure is printed on the can.

With 8 ft walls, one door and two windows, a 12 × 12 room has about 334 sq ft of wall. Two coats need about 1.9 gallons, so buy 2 gallons. Add roughly 0.8 gallons if you also paint the ceiling.

Usually, yes. A second coat evens out the color and sheen and makes the finish last longer. One coat can be enough when you repaint the same color over a clean wall. Dramatic color changes may need primer plus two coats.

Per gallon, usually yes. If you need 4 or more gallons of the same color, a 5-gallon bucket is often cheaper than four single gallons and keeps the color consistent across walls.

Prime new drywall, patched areas, bare wood, glossy surfaces and stains, or when going from a dark to a light color. Many "paint and primer" products can skip a separate primer on walls that are already painted and in good shape.