Roofing Calculators
Roofing is sold by the square, and the roof area is always larger than the footprint by a factor the pitch decides. Tear-off is priced separately from the new material.
There are 2 calculators here: 1,500 sq ft Roof Replacement Cost Calculator (roofing squares, bundles, tear-off and cost) and 2,000 sq ft Roof Replacement Cost Calculator (roofing squares, bundles, tear-off and cost).
They all work the same way: quantity first, then a waste allowance you can change, then a price built from verified figures and adjusted for your state. Cost is always a range rather than a single number, and every assumption behind it is printed on the page with its source and the date it was last checked.