Roofing
Roof Area Calculator
Your measurements : length, width, roof angle. Your estimate : net area, square feet, area to purchase.
How the calculation works
Roof Area Calculator
(Length + 2 × Horizontal overhang) × (Width + 2 × Horizontal overhang) ÷ cos(Roof angle°)Before you order
- A simple roof with one uniform pitch is assumed. Length and width are horizontal plan dimensions; overhang is horizontal on every side. Valleys, hips, dormers and overlaps need separate allowances.
- Planning estimate only. This is not a structural design, a safety approval or a local code check.
Worked example
- Length
- 5 m
- Width
- 4 m
- Roof angle
- 30 °
- Horizontal overhang
- 0.3 m
- Waste allowance
- 10 %
Net area 29.75 m²
Square feet 320.17 ft²