Roof pitch describes the slope of a roof. It's expressed as a ratio of vertical rise to horizontal run. For example, a 4/12 pitch means the roof rises 4 inches for every 12 inches of horizontal distance.
The calculator provides a reliable estimate for simple rectangular roof planes. Complex roof shapes with multiple valleys, hips, or dormers may require additional calculations. We recommend adding a 10–15% waste factor for such roofs.
A roofing square is a unit of measurement equal to 100 square feet of roof area. Shingles are typically sold in bundles, and most standard three‑tab shingles require 3 bundles to cover one square.
Cutting shingles to fit edges, valleys, and ridges always produces some unusable off‑cuts. A waste factor of 10% is standard for simple roofs. For complex shapes, 15% is safer.
No. All calculations are performed entirely in your browser using JavaScript. No data is sent to any server, and we don't use cookies or trackers.
The area calculation works for any roofing material, but the bundle and piece counts are calibrated for standard asphalt shingles. For metal panels or tiles, use the area figure and consult your material supplier for coverage rates.
Yes — completely free with no sign‑up required. We plan to keep the core calculator free forever.