What does this tool do?
Shingle quantity is measured in squares of 100 sq ft. This calculator applies the roof pitch factor to the footprint, adds 10% waste and converts squares to bundles at three bundles per square.
The Formula
Roof area = Length × Width × √(1 + (Pitch ÷ 12)²); Bundles = ⌈Squares × 1.10 × 3⌉Frequently Asked Questions
How many bundles are in a square?
Three bundles usually make one square (100 sq ft) of 3-tab or architectural shingles.
How much should I add for hips and valleys?
Add 10–15% for hips, valleys, starter strips and ridge caps; complex roofs need the higher figure.