Roofing Calculator
Estimate the sloped surface area of a simple symmetrical gable roof. Enter the building length and width, roof pitch and waste allowance.
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How the roofing calculator works
Estimate the sloped surface area of a simple symmetrical gable roof. Enter the building length and width, roof pitch and waste allowance.
For a symmetrical gable roof, sloped area is based on half the building width and the roof rise. This calculator then adds your selected waste percentage. The calculator is designed to give a useful first-pass material estimate while keeping the assumptions visible. For a purchase, compare the result with the product packaging or supplier quotation.
Common search terms for this tool include roofing calculator, roof area calculator, roof pitch calculator, how much roofing do I need. The wording is included naturally so the page answers the same questions people ask when planning a project.
Frequently asked questions
What is roof pitch?
Pitch describes how much the roof rises vertically for a horizontal run. In imperial units, a common format is rise per 12 inches.
Does this calculate a hip roof?
No. This first version is for a simple symmetrical gable roof.
What does the waste percentage cover?
Cuts, overlaps, breakage and layout waste. Manufacturer installation instructions remain the final reference.
Can I estimate shingles from this?
Yes. Use the total roof area with your shingle bundle coverage.