Step 1: Climb onto your roof with a pen, paper, and a long tape measure. You need to ensure that your tape measure is 60′ or longer to make sure you can achieve accurate results. Some walking tape measures are perfect for this situation.
Step 2: Next, you need to measure every edge around the perimeter of your home and section off each area on your paper diagram. Mark the measurements down next to each side on the paper when you pull them with your tape.
Step 3: Multiply two perpendicular sides on each section of your diagram to determine the square footage for each area of your roof.
Step 4: Once you have multiplied two sides for each section and figured out how many square feet each area is, you will need to add the numbers together to determine the total square footage of your roof. This measurement does not have to be super precise, because you are simply wanting a ball park figure for how much you should expect to pay.
Step 5: When you have the total square footage of the roof, you need to divide the number by 100. This is because metal roofing materials, installation, and service is sold at an average rate of $750 per square, or 10’x10′ (100 sq ft) area.