Question 1

How much paint do I need for a room of a given square footage?

Accepted Answer

One gallon of paint typically covers 350–400 sq ft with a single coat on a smooth, previously painted surface. For new drywall or dark colors, expect 300 sq ft per gallon. Always calculate your total paintable wall area (perimeter × wall height, minus doors and windows), multiply by number of coats, and divide by 350 to get gallons needed.

Question 2

How do I calculate wall area for a room with doors and windows?

Accepted Answer

Calculate total wall area first: (room perimeter × ceiling height). Then subtract unpainted areas: a standard interior door is about 20 sq ft, a standard window about 15 sq ft. This calculator handles all subtractions automatically.

Question 3

Should I buy extra paint? How much buffer is standard?

Accepted Answer

Yes — add 10% for waste, touch-ups, and coverage variance. So if you calculate 1.8 gallons needed, buy 2 gallons. Keep leftover paint sealed for touch-ups. For accent walls or complex colors, you cannot always return opened cans, so buy close to your calculated amount.

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