Shingle Roofing Calculator
Turn plan area and pitch into roof squares, shingle bundles, ridge caps and starter strips.
Enter your project details
Each dimension can use its own unit—for example feet for length and inches for thickness. Package counts are rounded up.
Formula and calculation steps
Roof surface = plan area × pitch multiplier × (1 + waste)- Plan area is 120 ft².
- Pitch 4:12 produces a 1.054× multiplier.
- Convert surface to squares and round packages up.
Worked example
For a 30 ft × 20 ft gable roof, enter the horizontal plan area once, pitch, ridge length and eave length.
How to use this calculator
- Enter plan area and roof pitch.
- Add ridge and eave lengths for trim pieces.
- Read squares, bundles, ridge caps and starter strips.
Example: For a 30 ft × 20 ft gable roof, enter the horizontal plan area once, pitch, ridge length and eave length.
Questions about this calculator
What is a roofing square?
One roofing square equals 100 square feet of roof surface area after pitch is applied.
How many bundles per square?
Most 3-tab and many laminate shingles use about 3 bundles per square; confirm with your product packaging.
Can I use mixed units?
Yes. Choose feet, inches, metres or centimetres and the calculator converts each input before calculating.
Is this a final material order?
No. Confirm drawings, product coverage, local code and site conditions before buying or building.
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<iframe src="https://www.buildcalclab.com/embed/roofing-calculator/?theme=light" width="100%" height="640" title="BuildWise calculator" style="border:0;max-width:720px"></iframe>Assumptions and references
Results are estimates based on the dimensions and values you enter. Verify final quantities, manufacturer coverage and site-specific requirements before ordering.
Last reviewed: July 2026 · Read our calculation methodology