How roofing material is estimated
Start with the measured roof area, add the selected waste allowance, and divide the adjusted area by 100 to calculate roofing squares.
Roofing calculation example
A 1,500-square-foot roof with 10% waste becomes 1,650 square feet of adjusted area, or 16.5 roofing squares.
How shingle bundles are calculated
Divide adjusted roof area by the stated coverage of one bundle. Different shingle products can cover different areas per bundle.
Valleys, hips, dormers, steep slopes and complicated roof geometry can increase cutting and waste.
Frequently asked questions
What is a roofing square?
A roofing square equals 100 square feet of roof area.
How many bundles are in a roofing square?
This depends on the product. Many shingles use roughly three bundles per square, but you should use the manufacturer's stated coverage.
Why add a waste allowance?
Cutting, overlaps and roof geometry can increase the amount of material needed beyond measured area.
Does this calculate roof area?
This calculator uses an area you already know. Use the Roof Square Footage Calculator to estimate roof area from dimensions and pitch.
Using this calculator effectively
The roofing calculator estimates roofing squares and shingle bundles from roof area and waste assumptions. It is useful for early material planning, but roof complexity and product packaging should be checked before purchase.
Common uses
- Estimating shingles for a simple roof area.
- Converting square feet of roof into roofing squares.
- Comparing material quantities under different waste allowances.
Tips for a better estimate
- Use true sloped roof area rather than only the building footprint.
- Increase waste for hips, valleys, dormers and complicated roof layouts.
- Check the bundle coverage stated by the shingle manufacturer before ordering.
Related calculations
Roof Shingle Calculator · Roof Pitch Calculator · Roof Slope Calculator