How to Calculate Shingles for a Gable Roof
- 1). Measure the horizontal length of the roof at the eave line or ridge from outside edge to outside edge across the roof’s surface.
- 2). Measure the vertical length of the roof section from the eave line to the ridge.
- 3). Multiply the horizontal dimension times the vertical dimension to define the roof section’s area in square feet. For example, a roof side that is 45 feet long and 19 feet from the eave to the ridge would be calculated by multiplying 45 times 19 to equal 855 square feet of surface area.
- 4). Multiply the area calculation you determined in Step 3 by 2 to establish the total roof surface area.