Roof Area Calculator
Calculate exact roof surface area based on footprint and pitch for accurate material ordering.
Quick Start
Step 1. Type
Flat or Pitched
Step 2. Measure
Base Dimensions
Step 3. Pitch
Angle or Ratio
Project Details
Check Configuration
Flat Roof
Pitched Roof
Base Dimensions (Footprint)
Enter the flat horizontal dimensions of the building, plus overhangs.
Footprint Area:0.00 m²
Results
Notes
New to Roofing?
Measuring Tips
1. Measure from the Ground
It's safer to measure dimensions from the ground. Add the overhang distance (eaves) to your length and width.
2. Pitch Matters
A steeper roof has significantly more area than a flat one with the same footprint. A 45° roof has ~41% more area than its footprint!
Help & Defaults
Pitch Ratios
In the US/Imperial, pitch is often "Rise over 12 Scale". E.g., 4:12 means for every 12 inches horizontal, it rises 4 inches.
Waste Factor
Simple gable roofs need ~10% waste. Complex roofs with hips and valleys may need 15-20%.