Roofing Shingles Calculator
Calculate roofing squares, shingle bundles, and nails needed based on your roof footprint and pitch.
This estimates a simple gable roof from ground footprint. For complex rooflines, measure the actual roof planes for a precise count.
Roofers price and order material in "squares" — one square covers 100 square feet of actual roof surface — but homeowners usually only know their building's ground footprint, not the sloped roof area, which is always larger. This calculator bridges that gap using the pitch multiplier: a steeper roof has more actual surface area than its footprint suggests, so a 6/12 pitch adds about 12% more area than the flat footprint, and steeper pitches add proportionally more.
Once the roof area in squares is known, standard 3-tab or architectural shingles need 3 bundles per square, and roofing nails run about 320 per square for a standard 4-nail-per-shingle pattern — both scaled up here by your waste factor to account for cuts, hips, and ridge caps.
Frequently Asked Questions
How many bundles of shingles are in a square?
Most architectural and 3-tab shingles are packaged 3 bundles per square (100 sq ft), though some heavier or designer shingles use 4-5 bundles per square — check the product packaging.
How do I convert roof pitch to actual roof area?
Multiply the flat footprint area by a pitch multiplier: sqrt(1 + (rise/12)^2). For a 6/12 roof that multiplier is about 1.118, meaning the real roof surface is about 12% larger than the footprint.