I would like to paint the exterior of a house how do I determine the square footage?

Do I measure the square foot of the house or the square foot of the walls when measuring to paint the exterior of a house?I would like to paint the exterior of a house how do I determine the square footage?
The square footage is the area that you are going to paint. You figure this out by measuring the perimeter of the house (the width of all exterior walls combined) and multiply that by the height of the walls. Then add 10% overage for general practice and purchase your paint based on that figure. Any paint can should say on the label how much square footage a certain amount of paint (like a gallon) will cover. If you're unsure, ask the people at the paint store.I would like to paint the exterior of a house how do I determine the square footage?
The sq of the walls is where the paint is going. Also the condition of the walls and how long it has been since it was last painted. What type of paint is on the wall now, you may need to use the same type, latex or oil? Take a little sample with you to the paint store and let them decide.