Shingle Calculator

Use actual coverage, not just a bundle count

A roofing square is 100 square feet. Bundle coverage depends on the selected shingle. The example coverage is approximately one-third of a square; use the manufacturer’s listed coverage for your product. Starter strips, ridge caps, underlayment and fasteners are separate products; the roofing calculator estimates starter, ridge cap, underlayment and drip edge from your roof edges.

Keep the geometry simple

The footprint method assumes one consistent pitch over the measured horizontal footprint, including overhangs. Complex roofs with dormers, valleys or mixed pitches need separate measured sections. This tool does not determine roof structure, flashing requirements or safe access.

Product reference: Owens Corning roofing product documents. Confirm the current label for your chosen product.

Already measured the roof surface?

Use the surface area directly in this tool. Do not apply a pitch multiplier a second time. For 1,500 square feet plus 10%, 1,650 square feet must be covered. At exactly 100/3 square feet per bundle, that is 49.5 bundles, rounded up to 50.

Bundles by roof size

For shingles packed three bundles per square (about 33.3 ft² per bundle), with a 10% allowance. These are roof surface areas, not floor areas.

If your 2,000 ft² is the house’s footprint rather than its roof, multiply by the pitch multiplier first. At 6:12 that becomes 2,236 ft² of roof surface and 74 bundles. Products packed four or five bundles per square need proportionally more bundles.