Paint Calculator (Gallons + Cost)
Gallons of paint and total cost for any room, single wall, ceiling, or exterior. Subtracts doors and windows, supports multiple coats.
LIFESTYLEGallons of paint and total cost for a room, single wall, ceiling, or entire exterior. Subtracts door and window area, accounts for multiple coats, and rounds up to the nearest quart since paint is sold in 1-gallon and 1-quart cans.
Coverage assumption: 1 gallon of interior latex covers ~350 sq ft on a smooth, primed surface (range 250-400 depending on surface texture, paint quality, and how generously you roll). Wall area = perimeter × ceiling height (2(L+W)·H for a room). Each door subtracts 21 sq ft (standard 3·7); each window subtracts 15 sq ft (typical 3·5). Total paint = (net area × coats) / coverage, then rounded up to the nearest 0.25 gallon.