Adjusted roof area--
Roofing squares--
Bundles with waste--
Roofing Shingle Calculator
Estimate roof area, roofing squares, shingle bundles, and waste before you order materials. This is built for quick planning, not a final roofing quote.
Updated May 2026No signup requiredBuilt for mobile
How to use this calculator
Enter the real measurements or counts you have now, run the calculator, then round the result in the practical direction before buying supplies or making a plan.
Formula or calculation method
Flat area = length x width
Adjusted roof area = flat area x pitch factor
Roofing squares = adjusted area / 100
Bundles = squares x bundles per square x waste factor
Practical examples
Example 1
A 40 ft by 28 ft roof with a 1.12 pitch factor is about 1,254 square feet, or 12.6 roofing squares before waste.
Example 2
With 10 percent waste and 3 bundles per square, that roof needs about 42 bundles after rounding up.
Useful assumptions
- One roofing square equals 100 square feet.
- Many asphalt shingles use 3 bundles per square, but verify your product.
- Waste varies by roof shape, cuts, valleys, and installer preference.
Common mistakes
- Forgetting roof pitch
- Ordering exactly the calculated amount with no waste
- Ignoring hips, valleys, starter rows, and ridge caps
- Mixing roof footprint area with actual roof surface area
FAQ
Roofing Shingle Calculator questions
What is a roofing square?
A roofing square is 100 square feet of roof surface.
How many bundles are in a roofing square?
Many asphalt shingles use 3 bundles per square, but some products differ. Check the package or supplier.
Should I include waste?
Yes. Roof cuts, valleys, hips, starter rows, and mistakes usually require extra material.
Does roof pitch matter?
Yes. A steeper roof has more surface area than the flat footprint.
Is this a professional quote?
No. It is a planning estimate. Confirm final quantities with your roofer or supplier.