Roof Area & Pitch Calculator — ft, rise:run, degrees
How to use this calculator
Calculate actual roof area from building footprint and pitch. Enter dimensions three ways: footprint + pitch (rise per 12″), rise + run measurements, or angle in degrees. Choose roof shape — gable, hip, or shed — and get instant results including pitch factor, actual area, rafter length, and an SVG profile diagram.
Multi-section — Add additional roof sections for complex roofs.
Pitch factor — The multiplier applied to footprint area to get true roof surface area, accounting for the slope.
Saved Calculations
| Time | Shape | Pitch | Footprint ft² | Roof Area ft² | Squares | Rafter |
|---|
How to Calculate Roof Area from Pitch
This utility calculator converts between roof pitch formats (rise:run, degrees, pitch factor) and calculates the actual roof surface area from building footprint dimensions. It supports gable, hip, and shed roof shapes with multi-section capability for complex roof geometries.
Formulas
Pitch factor (PF) = √(1 + (rise/12)²). Angle = arctan(rise/12) in degrees. Rafter length = run × PF. Gable area = footprint area × PF. Hip area ≈ footprint area × PF × 1.0 (same PF, all 4 sides sloped). Shed area = footprint area × PF (single slope).
Common Pitches
2:12 = 9.5° (low slope, minimum for shingles) · 4:12 = 18.4° (standard residential) · 6:12 = 26.6° (steep) · 8:12 = 33.7° (very steep) · 12:12 = 45° (equal rise and run).
FAQ
What is a roofing square? One square = 100 ft² of roof area. Roofing materials are often sold by the square.
How does hip differ from gable? A hip roof has all four sides sloped. The pitch factor applies to all sides, but the total footprint coverage is the same — both use PF × footprint area for actual roof area.
