After you have done the multiplication, subtract about 40 sq feet per window, and about 60 sq feet per door. Divide by 400 (interior paint covers 400 sq feet per gallon). The number that remains, is how many gallons you will need. If doing multiple wall colors, then you should do this process for each room (or sets of rooms) with a particular color.  House Painting
There's an insurmountable number of popular interior paint colors you can choose. Deciding which shade is one thing, and figuring out what room to cover it in is a whole other beast. That is why we narrowed down your choices to a handful of tried and true shades favored by decorating experts for various rooms to help make your decision a little easier. House Painting
Sherwin-Williams color trend expert Sue Wadden considers Poised Taupe (SW 6039) a gorgeous neutral shade with timeless versatility and broad appeal. "It's a lovely color that people fall hard for because the shade is very easy to live with—it is stunning paired with white. It also works well with a palette of blues, especially denim and country blue colors."
After you have done the multiplication, subtract about 40 sq feet per window, and about 60 sq feet per door. Divide by 400 (interior paint covers 400 sq feet per gallon). The number that remains, is how many gallons you will need. If doing multiple wall colors, then you should do this process for each room (or sets of rooms) with a particular color. 
If you have kids, pets, or occupants who will damage the walls, it is recommended to go with washable matte, eggshell, or satin, because these paints can be easily cleaned and are more durable. However, flat paint can be touched up more easily and hides imperfections better, so if you are selling the home, it is highly recommended to go with flat. Bathrooms with showers/tubs should go in semigloss- unless you are selling or want a specific design look, then use satin.  House Painting
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