Paint Calculator
Enter the room size and this gives you the gallons for the walls, the ceiling and the primer, with the doors and windows taken out of the area.
How the math works
Wall area = the perimeter of the room x the wall height, then take off 21 sq ft per door and 15 sq ft per window. Gallons = area x coats, divided by 350, because a gallon covers about 350 square feet on a smooth sealed wall.
Common questions
- How much paint do I need for a 12 by 14 foot room?
- About 2 gallons for two coats on the walls. The walls are 416 square feet gross, roughly 365 after one door and two windows, and 365 doubled and divided by 350 comes to a touch over 2 gallons.
- How many square feet does a gallon of paint cover?
- About 350 on a smooth, sealed wall. New drywall, bare wood and rough texture drink more, closer to 250 to 300, so prime first rather than buying a third coat.
- Do I really need two coats?
- Nearly always. One coat only works when you are putting a similar color over sound existing paint. Dark colors, and red in particular, often need three whatever the can promises.
- Should I subtract doors and windows?
- Yes, and this calculator does. On a small room the openings can be a fifth of the wall area, which is the difference between buying two gallons and buying three.
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