Paint Calculator

One gallon of standard interior paint covers approximately 350-400 square feet per coat on smooth, primed surfaces. Rough or textured walls absorb more paint and may only get 250-300 square feet per gallon. Always buy slightly more than calculated — having leftover paint is much better than running short mid-wall.

You need primer if painting over new drywall, bare wood, a dark color with a light color, stains or water damage, or glossy surfaces. Many modern paints include primer (paint + primer in one), which works well for repainting similar colors on already-painted walls. For major color changes or new surfaces, a dedicated primer gives better results.