Roofing Calculator

What Is a Roofing Square?

One roofing square = 100 sq ft. Roofing materials are typically sold by the square. Standard 3-tab shingles come 3 bundles per square; architectural shingles often require 4 bundles per square — confirm with your supplier.

Pitch Factor

A roof's actual area is larger than its footprint because it's sloped. The pitch factor accounts for this: a 6/12 pitch adds about 12% more area than the flat footprint. Steeper roofs have larger factors and use more material.

What to Order

In addition to shingles, budget for: felt underlayment (1 roll per square), drip edge (linear footage of eaves + rakes), ridge cap shingles (linear ft of ridge), and roofing nails (about 2.5 lbs per square).