To estimate the gallons of paint required for a paint job, divide the total square footage of the surface area to be painted by 350, according to Dummies.com. The number, 350, represents the square footage that a gallon of paint typically covers.Continue Reading
To estimate the amount of paint needed for a 10-foot by 15-foot room with 9-foot ceilings, one door and one window, first figure out the area of the ceiling. Ceiling paint is different from wall paint. The ceiling area would be: 10 x 15 = 150 square feet. Divide this by 350 to get the amount of ceiling paint needed: 150/350 = 0.43 gallons, which rounds up to two quarts.
For the wall paint, measure the area of the four walls. The total of two of the walls would measure: 2 x 10 x 9 = 180 square feet. The other two walls together would measure: 2 x 15 x 9 = 270 square feet. Adding them up yields: 180 + 270 = 450 square feet.
A standard door measures 20 square feet and a standard window is 15 square feet. Subtract these measurements from 450 to get the total paintable surface area: 450 - 20 - 15 = 415 square feet. Divide 415 by 350 to get the number of gallons of paint needed: 415/350 = 1.2. About one gallon and one quart of wall paint would be required. This is only good for one coat of paint, so additional coats require additional paint.Learn more about Home Maintenance