Paintable wall area and gallons of paint needed for any room, with doors and windows subtracted.
Coverage assumes about 350 ft² per gallon per coat, rounded up.
Wall area = room perimeter (2 × (length + width)) × ceiling height, unless you enter a total wall area directly. We subtract about 21 ft² per door and 15 ft² per window to get the paintable area. Total coverage = paintable area × coats, and gallons = total coverage ÷ 350 ft² per gallon, rounded up.
Painting a ceiling, floor or odd-shaped wall? Get the raw area first with our square footage calculator and drop it into the total wall area field. Every tool lives on the calculator hub.
Interior paint, primer, rollers and tape delivered to your door.
Wall area minus doors and windows, times coats, divided by ~350 ft² per gallon. Most average rooms take 1–2 gallons per coat.
About 350 ft² per coat on smooth, primed drywall. Rough or porous walls cover less.
Two is standard. One coat over a matching color, three when going dark to light.
Yes – about 21 ft² per door and 15 ft² per window so you don't overbuy.
A little extra helps for touch-ups. Rounding gallons up usually covers it.