How to use this calculator
- Choose known area or pitched dimensions.
- Enter the roof area or footprint dimensions and pitch.
- Set waste and the coverage printed for the bundle you plan to use.
- Calculate roofing squares and whole bundle quantity.
How the calculation works
A known area is converted to square feet, or dimensions are multiplied by the pitch multiplier. Waste is applied, then adjusted area is divided by the entered bundle coverage and rounded upward.
Formula
Adjusted area = roof area × (1 + waste % ÷ 100) Roofing squares = adjusted square feet ÷ 100 Bundles = adjusted square feet ÷ coverage per bundle, rounded up
Worked example
A 1,000 square foot roof with 10% waste requires coverage for 1,100 square feet, or 11 roofing squares. At 33.33 square feet per bundle, the result is 34 whole bundles.
Project considerations
- Bundle coverage is editable because products and packaging vary.
- Verify current coverage and installation instructions for the selected product.
- Starter strips, ridge caps, underlayment, flashing, and fasteners are not included.
Frequently asked questions
Why are bundles rounded up?
A fractional bundle cannot cover the remaining calculated area, so purchase quantity is rounded to a whole bundle.
Does every roofing square require three bundles?
No universal bundle count is assumed. The calculator uses the editable square-foot coverage entered for one bundle.