Roofing Shingles Calculator
Calculate the squares and bundles of shingles you need using your roof's footprint and slope factor, with a waste allowance built in.
Bundles needed
45bundles
Squares needed
14.76sq
Roof area
1342ft²
A roofing square is 100 sq ft of actual roof surface. Your building footprint isn't the same as roof area — multiply it by the slope factor first, which the Roof Pitch Calculator gives you.
How the roofing shingles calculator works
Shingle quantities are calculated from actual roof surface area, not the flat footprint of the building — a roof with any pitch always has more surface area than the ground it covers.
Formula: roof area = footprint (length × width) × slope factor. Total with waste = roof area × (1 + waste% ÷ 100). Squares = total ÷ 100. Bundles = squares × bundles per square, rounded up.
Don't know your slope factor? Head to the Roof Pitch Calculator first, enter your rise and run, and bring the slope factor back here.
Frequently asked questions
A square is the standard unit roofing material is bought and sold in — 100 square feet of actual roof surface, not building footprint. Dividing your total roof area by 100 tells you how many squares to order.
3 bundles per square is standard for most 3-tab and architectural shingles, each bundle covering roughly 33 sq ft with typical exposure. Some heavier architectural or designer shingles are packaged 4 bundles per square — check your specific product.
Multiply your building's footprint (length × width) by a slope factor that accounts for your roof's pitch — a steeper roof has more actual surface area than its footprint suggests. Use the Roof Pitch Calculator to get your exact slope factor from your rise and run.
10% covers a simple gable roof. Hip roofs need closer to 15%, and roofs with multiple valleys, dormers, or complex cuts can need 20% or more.