Roofing Calculator
Estimate roof squares, shingle bundles, and cost
Frequently Asked Questions
Roof area = footprint area (length × width) × a pitch multiplier that accounts for the roof's slope. A steeper roof has more actual surface area than its flat footprint suggests — the pitch multiplier is √(1 + (rise ÷ 12)²), so a 6/12 pitch (rise of 6 inches per 12 inches of run) has a multiplier of about 1.118.
A square is the standard roofing trade unit: 100 square feet of roof surface, regardless of shingle type or brand. It's the unit contractors and suppliers use to quote materials and labor.
Standard asphalt shingles are typically packaged 3 bundles per square, though some heavier or specialty shingles use a different bundle count — check your specific product's coverage rating.
A simple gable roof typically needs about 10-15% waste, while hip roofs or roofs with multiple valleys, dormers, and complex cuts often need 20-25% to account for the extra trim loss.
No — this calculator estimates total roof area and applies a waste-factor allowance for cuts, which is accurate enough for material budgeting on most roofs. It doesn't compute exact hip, valley, or jack rafter lengths and angles — that level of framing detail needs a dedicated framing calculator or a roofer's on-site measurement.