Roofing Calculator – Shingles and Bundles for Your Roof
Free roofing calculator: enter roof dimensions and pitch to estimate shingle bundles needed. Plan material orders for reroofing or new construction. No sign-up, runs in your browser.
Roofing Calculator
Estimate shingle bundles for a roof. Enter footprint dimensions in feet. Pitch factor ~1.15 for 4/12 pitch.
How the roofing calculator works
roof_area = length × width × pitch_factor
bundles_needed = ceil(roof_area ÷ bundle_coverage)
Pitch factor accounts for slope; steeper roofs have more surface area than the footprint. Add 10–15% for waste.
Estimating roofing materials
Replacing a roof or building new requires accurate material estimates. Ordering too few bundles means delays and possible color mismatches; ordering too many wastes money. Measure your roof footprint (length and width), apply a pitch factor for slope, and divide by the coverage per bundle. Standard 3-tab shingles cover about 33 square feet per bundle; architectural shingles may differ. Always add 10–15% for waste, hips, ridges and starter courses.
Roof pitch is expressed as rise over run (e.g. 4/12 means 4 inches of vertical rise per 12 inches of horizontal run). Steeper roofs have more surface area, so the pitch factor increases. A 4/12 pitch often uses 1.15; 6/12 might use 1.2. Check manufacturer specs for your specific product. Our area calculator helps with flat roof measurements; the paint calculator estimates wall coverage for siding projects.