A material which is used to prevent the flow of heat, sound, electricity from anything is called as insulators. The roll insulation is the most commonly used insulation in houses. Before buying the roll insulation, the area of the room where it should be insulated should be calculated. Here is a roll insulation formula to calculate the area which needs to be insulated. The square feet needed to be insulated can be calculated by multiplying the width and height of the area.