Use this calculator to estimate the amount of paint needed for your interior project.
Room Perimeter: Feet Inches
Wall Height: Feet Inches
Number of...
    Single Doors @ 20 sq feet
    Double Doors @ 40 sq feet
    Small Windows @ 10 sq feet
    Large Windows @ 25 sq feet
Painting over new primer or paint? Primer   Paint
Gallons of paint needed: = Total

Most interior paints provide approximately 375 to 400 square feet of coverage per gallon. Be sure to check the label of the specific Glidden paint product for your project.