Calculate how many gallons of paint and primer you need for room walls, doors, windows, and ceilings.
One standard US gallon of quality paint (Sherwin-Williams, Benjamin Moore, Behr) covers approximately 350 to 400 square feet on smooth, primed walls. Textured walls or unprimed drywall absorb more paint, reducing coverage to 300 square feet per gallon.
Yes. A second coat ensures consistent sheen (especially with satin, eggshell, or semi-gloss finishes), eliminates roller lap marks, and prevents old wall paint colors from bleeding through.
Use a dedicated primer if painting over bare drywall, patching with joint compound, covering water/smoke stains, painting glossy surfaces, or making a dramatic color transition (such as dark navy to off-white).