Calculate roofing materials by pitch and complexity
A roofing calculator estimates shingles, underlayment, and materials based on roof size and pitch. Accurate calculations prevent costly shortages or overages.
Roof Area = Footprint × Pitch Factor; Squares = Area / 100
A roofing square equals 100 square feet of roof area. Shingles are sold in bundles, typically 3 bundles per square. This standardized measurement simplifies material ordering and contractor quotes.
Steeper roofs have more surface area than the footprint suggests. A 6/12 pitch multiplies area by 1.12. A 12/12 pitch multiplies by 1.41. Higher pitch = more materials and labor cost.
Most asphalt shingles: 3 bundles per square. Some architectural shingles: 4-5 bundles per square. Check manufacturer specifications. Buy extra for waste and future repairs.
15 lb felt: Budget option, good for moderate climates. 30 lb felt: Better durability, required in some codes. Synthetic: Premium choice, longer lasting, required for metal roofs.
Starter strip: Equal to roof perimeter in linear feet. Ridge cap: Equal to total ridge and hip length. One bundle of ridge cap covers about 31 linear feet.
Required in cold climates along eaves (3 feet minimum). Recommended around valleys, skylights, and penetrations. Self-adhering membrane that prevents ice dam damage.