A walkthrough, end to end.
- 1
Enter the building footprint length and width.
- 2
Enter the roof pitch (rise per 12 inches of run).
- 3
See total roof area, squares, and shingle bundles needed (3 bundles per square).
Roof area
Multiplier = √(1 + (pitch/12)²). Roof area = footprint × multiplier × 2 sides (gable). 1 square = 100 sq ft = 3 bundles.
What you can do with this.
Re-roof estimate
Quickly plan shingle bundle count for a tear-off.
Material budgeting
Multiply bundles × price for a rough cost.
Comparing pitches
See how steeper roofs need more shingles.
Ridge cap
Approximate hip and ridge bundles separately (typically 1 per 30 LF).
Underlayment
Same square count applies to felt or synthetic.
Insurance claims
Cross-check supplier estimates.
Solar planning
Roof area helps size potential PV arrays.
Roofing 2026 — what's current
Standard estimating; calculator wins for instant pitch math.
Frequently asked.
Standard residential is 6/12. Steeper roofs (10/12+) significantly increase area.
Standard 3-tab and architectural shingles are 3 bundles per square.
Add 10–15% extra for cuts on hips, valleys, and ridges.
No. All math runs in your browser.