Roof area calculator
Calculate sloped roof area from horizontal length, full width and roof angle.
- Sloping area
- —
- Horizontal footprint
- —
Enter both dimensions and the roof angle.
Measure the horizontal roof footprint, including overhangs. Horizontal dimensions of the area covered, not dimensions measured along the slope.
In Pro², add sheet dimensions or pack coverage and an allowance to estimate material quantities.
View Pro² on the App StoreBrowser calculation is free. Pro² has limited free use; unlimited calculations and PNG/PDF export require paid access.
A worked example
A = L × W / cos(θ)
Enter one rectangle and one pitch. Split a roof with several pitches or non-rectangular regions into suitable separate area estimates.
Do I halve the width of a gable roof?
Not when estimating both equal slopes together. The full plan width already covers both halves; calculate only one half if you intend to estimate one slope.
- L × W; θ
- 10 × 8 m; 30°
- Sloping area
- 92.38 m²
What you get
Area only. No waste allowance or material quantities.
This tool estimates covering material. It does not size rafters, check roof loads or design the roof structure.