The average roof size for homes in the U.S. is 1,700 square feet, or 17 squares of shingles. However, larger homes with garages often exceed 3,000 square feet, or 30 squares, of roof space.
Since it can be difficult and dangerous to climb on the roof and measure it yourself, you can estimate the size of your roof by multiplying your home's square footage by 1.5. For example, a 2,000 square foot house will need about 3,000 square feet, or 30 squares, of shingles.