Roofing Calculator
Estimates the number of roofing bundles from roof area, waste allowance and coverage per bundle.
How it works
Roofing bundles with waste
Formula and assumptions
Bundles = round up(roof area × (1 + waste percentage ÷ 100) ÷ coverage per bundle). Confirm whether the supplier’s coverage is stated per bundle and account for roof complexity and local installation guidance.
Example
Use the sample values, calculate, and change one input at a time.
Frequently asked questions
Are results exact? Results depend on the assumptions and inputs above.
Can I use this for professional decisions? Verify critical results independently.
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Frequently asked questions
Does it account for roof shape and pitch?
Only if your entered roof area already reflects the actual roof surface; measure carefully and confirm bundle coverage.
What should I check before relying on the result?
Confirm the input units and assumptions described above; independently verify safety-critical, medical, financial or professional decisions.
What measurements should I enter?
Enter the roof area in the units shown by the calculator, then provide the waste percentage and coverage per bundle from your roofing product.
How much extra roofing material should I allow?
Waste depends on roof complexity, cuts, valleys, ridges and installation pattern. Use a project-appropriate allowance and confirm it with your roofer or supplier.