What is a Roofing Square?
A roofing square equals 100 square feet of roof surface. It's the standard unit roofers use when ordering and pricing shingles. Most architectural shingles come in 3 bundles per square, though heavier products may need 4 bundles. Use our free calculator above to get your square and bundle count based on footprint and pitch.
Pitch Factor Chart
| Pitch | Slope Factor | Classification |
|---|---|---|
| 2:12 | 1.02× | Low slope |
| 4:12 | 1.05× | Conventional |
| 6:12 | 1.12× | Moderate |
| 8:12 | 1.20× | Steep |
| 12:12 | 1.41× | Very steep |
Frequently Asked Questions
How many bundles of shingles do I need per square?+
Standard 3-tab and architectural (dimensional) shingles come 3 bundles per square (100 sq ft). Heavier premium shingles may require 4 bundles per square — always check the product packaging.
How many squares of shingles for a 1,500 sq ft house?+
The roof area is larger than the house footprint due to pitch. A 1,500 sq ft house with a 4:12 pitch has approximately 1,575 sq ft of roof area (multiply by 1.05 pitch factor). That's about 17 squares or 51 bundles, plus starter course and ridge cap.
How long do architectural shingles last?+
Quality architectural (dimensional) shingles are rated for 25–30 years and often last 20–25 years in practice. Premium Class 4 impact-resistant shingles can last 30–40 years and may qualify for insurance discounts.
What is the minimum pitch for asphalt shingles?+
Standard asphalt shingles require a minimum 2:12 pitch with special underlayment installation. Below 2:12, you need a membrane roofing system (low-slope materials). Most manufacturers recommend 4:12 or steeper for best performance.