How Many Shingles Do I Need?

A sloped roof always has more surface area than the building's flat footprint — the steeper the pitch, the bigger the gap. The conversion factor is √(1 + (rise/12)²): a 6/12 pitch multiplies footprint area by about 1.118, a 12/12 pitch by about 1.414.

Roofing material is sold in "squares" — 100 sq ft each — and most shingle products are packaged 3 bundles per square. A waste allowance (10% is typical) covers cuts around edges, valleys, and roof penetrations like vents and chimneys.

The Roofing Calculator handles the pitch-adjusted area and converts straight to squares and bundles from your building's footprint and pitch.

Architectural (dimensional) shingles typically weigh more and are sometimes packaged 4 bundles per square instead of the standard 3, depending on the product. Always check the specific product's coverage-per-bundle figure on the wrapper rather than assuming the standard rule.