Roofing Calculator
Calculate sloped roof area and shingle bundles from the building footprint and roof pitch.
Estimates for planning purposes only. Verify measurements, add a 10% waste allowance, and consult a licensed roofing contractor for final quantities.
How it works
- 1Enter the building’s length and width to define the plan footprint area.
- 2Select the roof pitch — the rise-over-run ratio that sets how steep the slope is.
- 3The calculator applies the pitch factor √(1 + (rise/run)²) to give the true sloped area and the shingle bundles required.
Use cases
- Estimating shingle quantities before ordering materials for a new roof.
- Comparing material costs across different roof pitches during design.
- Quick take-offs for roofing contractors bidding residential jobs.
Frequently asked questions
Why is the roof area larger than the footprint?
A sloped roof covers more surface than the ground below it. The pitch factor √(1 + (rise/run)²) sets the increase — for a 6:12 pitch it is about 1.118, so an 80 m² footprint becomes roughly 89.4 m² of roof.
How many bundles of shingles do I need?
Asphalt shingles come about 3 bundles per roofing square (100 ft² / 9.29 m²). This calculator rounds up to whole bundles; always add at least 10% for waste and cuts.
What is a roofing square?
A roofing square equals 100 square feet (about 9.29 m²). Contractors price labour and materials per square, so the square count helps you get accurate quotes.
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