How do I calculate to figure out for interior paint amount needed?

Want to paint interior walls and ceilings of my house and want to know what formula to use to figure out how much paint I iwill needHow do I calculate to figure out for interior paint amount needed?
example for walls and ceilings:





1600 sq ft of surface x 2 coats= 3200 divided by 400=8 gal.





example for trim: for 4'; of trim x 12' multiply .75 x 12'= 9 sq ft.


add up the amount of square footage for all trim and follow the first formula.How do I calculate to figure out for interior paint amount needed?
Width of the wall times height equals square feet.
A gallon of most kinds of interior paint will cover between 300 and 400 square feet. Finish paint will go further if the walls have been primer coated, particularly if the primer has been tinted to match the paint.





Plan on two coats. More if applying a dark color.
Measure along the floor the length of all your walls, (four walls per square room), Round measuremnts up to the next largest foot (11ft 8 in is 12ft). This helps for simple math. Add all four measurements and multiply that number by the height (8 ft is the normal height of all walls). That gives you square footage of wall surface. One gallon of paint covers approximately 250 square feet. To calculate the ceiling, measure width and length (both directions). Multiplying those 2 numbers together to get the ceiling square footage. 12 ft wide by 12 foot long room will be 144 square feet of ceiling space. So you should purchase 1 gallon of ceiling paint. Same room (12 +12+12+12= 48 X 8= 384 sq ft of wall space). So you should buy 2 gallons of paint for your walls. So in all, you would need 3 gallons of paint. Suggested flat paint for ceilings, and eggshell or semi gloss for walls. If trim or moldings to be different color, use gloss. ( remember drop cloths LOL) Have fun!
It's square footage alright but some of these other figures are wrong.


A gallon of ';contractors paint'; the cheaper stuff will barely cover 250 square and not show through, you may even need a second coat.





If you use a good primer and a good intermediate paint, then you should be O.K. for about 250 to 300 square feet. And, the way you put it on will also make a difference for painting a large area.





I once sprayed a two story condo with a Sears special paint that was on sale, the owner bought it. I don't like doing it this way and told her I was not responsible, she insisted.





With my big gun, two of us, we did the entire unit before the first room dried. We came back the next day to her crying, the paint was like water on the wall, it all showed through. She sued but, sears sent out a rep. and, took samples, they didn't have enough pigment in the paint and, sold it as a special. They paid for another paint job.





Be careful where you get the paint and, if it's worth painting, it's worth doing it right.
Figure sq ft.


Look on paint for coverage.


1 10'x8' wall=80 sq ft
go to this site!