Roofing Calculator (Squares & Shingles)
Calculate roof area from the house footprint and roof pitch, then the roofing squares, shingle bundles, underlayment rolls and cost.
How to use
- 1Enter the building footprint (length × width, including overhangs) and the roof pitch (rise per 12 in of run).
- 2Add waste — more for complex roofs with valleys and hips.
How it's calculated
Pitch factor = √(1 + (rise ÷ 12)²). Roof area = footprint × pitch factor. Squares = area ÷ 100 × (1 + waste). Three-tab and architectural shingles: 3 bundles per square.
Frequently asked questions
What is a roofing square?
100 square feet of roof surface.
How much waste should I add?
About 10% for simple gable roofs and 15–20% for hip roofs or roofs with dormers and valleys.
How do I measure pitch?
Hold a level horizontally against the roof, measure 12 in along it, then measure vertically to the roof surface — that's the rise.