Roofing Calculator
Assumes standard 3-tab or architectural shingles at 3 bundles per square (100 ft²) — some premium shingles use 4 bundles per square, so check your product's coverage. A steeper pitch means more actual surface area than the building's footprint alone suggests.
Free roofing calculator that converts your building's footprint and roof pitch into actual roof surface area, squares, and shingle bundles needed — accounting for the extra surface a steeper pitch adds.
How it works
- Enter your building's footprint area and roof pitch (rise per 12" of run)
- Set a waste factor for cuts, hips, and valleys
- See the actual roof surface area, squares, and shingle bundles needed
Frequently asked questions
Why is the roof area bigger than my building's footprint?
A sloped roof has more actual surface area than the flat footprint below it — the steeper the pitch, the bigger the difference. This calculator applies the standard pitch-to-area multiplier (based on the Pythagorean theorem) automatically.
What's a "square" in roofing?
A roofing square is 100 square feet of roof surface — the standard unit contractors and shingle manufacturers use, rather than raw square footage.
How much waste factor should I use?
10% is a common default for a simple roof. Roofs with more hips, valleys, and cut angles need more — 15-20% isn't unusual for a complex roof.
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Update history
- 2026-09-01 Launched: roofing calculator converting footprint + pitch into actual roof area, squares, and shingle bundle counts with an adjustable waste factor. Entirely client-side.