How Much Paint Do I Need?
Updated
To estimate paint, calculate wall area (perimeter × height), subtract about 21 sq ft per door or window, multiply by the number of coats, and divide by 350 (sq ft per gallon). A standard 12×12 ft room needs about 2 gallons for two coats.
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Coverage rates
One gallon covers roughly 350–400 sq ft per coat on smooth, primed walls. Textured, porous, or unprimed surfaces absorb more and cover less.
One coat or two?
Plan on two coats for durable, even color — especially over fresh drywall or when changing colors. Buy 5–10% extra so you have a dye-lot match for touch-ups.