Asphalt Shingles vs. Metal Roofing Comparison
Compare durability, cost, and lifespan of the most popular roofing materials.
Read the guide →Roofing Calculator
Calculate roofing squares, shingles, and material cost for your roof replacement project.
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How This Calculator Works
This roofing calculator estimates the number of squares (100 sq ft units) of roofing material, underlayment rolls, and ridge vent length needed for a standard gable roof.
How it works:
- Roof area: Building footprint × roof pitch factor. The calculator assumes a 1-ft overhang on each side. A 4:12 pitch has a factor of 1.054 (the slope adds 5.4% more area than the footprint). An 8:12 pitch has a factor of 1.202 (20.2% more).
- Shingles: 1 square (100 sq ft) of roof needs 3-4 bundles of asphalt shingles depending on the shingle profile. A typical home needs roughly 20-30 squares.
- Underlayment: 1 roll covers 4 squares (400 sq ft) at standard 4-inch overlaps. For low-slope roofs (2:12 to 4:12), double the underlayment.
Example: A 1,500 sq ft single-story home with a 6:12 pitch roof (assuming 1-ft overhang each side) has roughly 975 sq ft of roof per side = 1,950 sq ft total = 19.5 squares. That's approximately 60-78 bundles of architectural shingles. See our roof pitch compatibility guide for low-slope underlayment requirements.
Helpful Roofing Calculator Resources
Roof Pitch and Material Compatibility Guide
How roof slope affects material choices, installation methods, and underlayment requirements.
Read the guide →How to Spot Roof Damage Before It Leaks
Warning signs, common damage patterns, and when to call a roofer for an inspection.
Read the guide →