You're ready to re-do your roof and it's time to purchase the materials. You've measured your roof and calculated the area in square feet. When you get to the home improvement store, you find out the roofing materials are sold by the linear foot. It's easy to convert a measurement in terms of square feet to one in terms of linear feet.
Measure the length and width of your roof in inches. Multiply the roof's length by its width to get the total roof area in terms of inches.
Determine the width in inches of your proposed roof shingles or other materials.
Divide the total roof area in inches (the figure you calculated in Step 1) by the width of your proposed shingles in inches (determined in Step 2). This figure is the area of your roof in linear inches.
Divide the area of your roof in linear inches (calculated in Step 3) by 12 to convert the inches to feet. The resulting figure is the area of your roof in linear feet. This is the figure you need to determine the correct amount of materials when purchasing by the linear foot.