Roof Shingle Calculator

Estimate asphalt shingle bundles, roofing squares, waste, and spare coverage from measured roof area or footprint plus pitch. Calculations stay in your browser.

Project inputs

Use the roof surface area when you already have it. Use footprint mode for a quick estimate from plan dimensions and pitch.

Overhang allowance is added to both length and width before applying the pitch factor.

Results

Total bundles to order
0 bundles
Enter roof details and calculate to see the estimate.
Roof surface area0 ft²
Waste-adjusted area0 ft²
Exact squares0 squares
Whole squares0 squares
Base bundles0 bundles
Spare coverage after rounding0 ft²

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Formulas and assumptions

A roofing square is 100 square feet of installed roof coverage. Shingle bundle coverage varies by product, so this calculator lets you enter the coverage printed on the wrapper or choose a common bundles-per-square preset.

  • Pitch factor: sqrt(1 + (rise / 12)^2)
  • Roof area from footprint: (length + overhang) x (width + overhang) x pitch factor
  • Waste-adjusted area: roof area x (1 + waste% / 100)
  • Exact squares: waste-adjusted area / 100
  • Base bundles: ceil(waste-adjusted area / bundle coverage)
  • Total bundles: base bundles + additional bundles

Footprint mode is an estimating shortcut. Measured roof planes, takeoff drawings, or supplier measurements are better for complex roofs.

How to measure for shingles

  1. Measure each roof plane or use a roof takeoff when available. Add all plane areas before entering the roof surface area.
  2. If you only know the building footprint, enter footprint dimensions and pitch for an approximate sloped roof area.
  3. Use the product's bundle coverage. Standard asphalt shingles are often 3 bundles per square, but product packaging controls.
  4. Add waste for cuts, valleys, hips, rakes, damage, and layout complexity before rounding up to bundles.
  5. Add separate starter, ridge, hip, repair, or attic-stock bundles when those products are supplied separately.

Waste guidance

Use waste as an estimating allowance, not a code rule. A simple rectangular gable roof may be close with 10% waste. Roofs with hips, valleys, dormers, skylights, chimneys, steep slopes, cut-up plans, or multiple shingle colors may need 12% to 20% or more. Manufacturer instructions and installer practice should guide final ordering.

This calculator does not design the roof system, verify fastening, check ventilation, or confirm whether asphalt shingles are suitable for the roof slope. Follow local building code, product installation instructions, and safety requirements.

Roof shingle FAQs

Should I order by bundles or squares?

Suppliers often price by bundle and discuss roof size by square. This tool shows both, then rounds bundle count up because bundles are whole packages.

Why does the whole-square number differ from bundle count?

Whole squares round the area to the next 100 sq ft. Bundle count rounds by product coverage. When bundle coverage is not exactly one-third of a square, the two rounded numbers can differ.

Does pitch mode work for hip roofs?

It approximates total sloped area from the horizontal projection and pitch. For precise hip, valley, dormer, or multi-plane roofs, enter measured surface area instead.

Should ridge caps be included in waste?

Some projects cut ridge caps from field shingles; others use dedicated hip and ridge products. Use the additional bundles field for a clear separate allowance when needed.

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