Roof Area Calculator

Calculate your total roof area from the building footprint and roof pitch, accounting for overhangs and complexity.

Results

Visualization

How It Works

Roof area is NOT the same as building footprint. The steeper the pitch, the more surface area the roof has. A pitch factor converts flat footprint area to actual sloped area using the formula: pitch_factor = sqrt(1 + (rise/12)^2). For example, a 6/12 pitch has a factor of 1.118, meaning 12% more area than a flat roof. Always add overhangs (typically 6-18 inches) to your footprint before calculating. Complex roof shapes with hips, valleys, and dormers add 15-30% more material due to cuts and waste.