How much does a gallon of paint cover?
About 350–400 sq ft per coat on smooth primed drywall. Textured, porous or unprimed surfaces can drop that to 250 sq ft.
Calculate exactly how much paint you need for any room. Enter room dimensions, number of coats, and door/window areas for accurate estimates.
Wall area = perimeter × height − doors and windows. Gallons per coat = wall area ÷ 350. Total = gallons per coat × coats.
A 12 × 14 ft room with 9 ft ceilings has 468 sq ft of wall, less 40 sq ft of openings = 428 sq ft. That is 1.2 gallons per coat, so buy 3 gallons for two coats plus ceiling.
About 350–400 sq ft per coat on smooth primed drywall. Textured, porous or unprimed surfaces can drop that to 250 sq ft.
Over the same colour, one coat is often enough. Two are standard for a colour change, and a tinted primer is essential over dark colours or bare drywall.
Yes for anything above about 15 sq ft. Ignoring a patio door or large window can overstate paint needs by a full gallon.