Single shed section
Input
L=10m, D=4m, Pitch=30°, Overhang e=0.45m
Output
Ap=44.50m², As=51.38m², k=1.1547
Roof Area and Pitch Calculator
Calculate sloped roof area from horizontal plan dimensions and pitch.
For complex roofs, split the plan into sections and combine the totals in one result.
All dimensions are treated as horizontal projections
Combine shed and gable sections
Convert degrees, Rise:Run, %, and sun slope
How to use
- Select a unit (m/mm), then enter the section shape and plan dimensions.
- Choose a pitch format (degrees, Rise:Run, %, or sun) and enter the values.
- Enter overhang, then add sections if the roof needs split input.
- Review the summary and breakdown, then copy, share the URL, or print.
Examples
L-shape roof split into 2 sections
Input
Section 1: Gable / Section 2: Shed
Output
Sum Ap/As from each section to get total
Formulas
- r = Rise / Run
- k = sqrt(1 + r^2)
- Shed Ap = (L + 2g) × (D + e + e2)
- Gable Ap = (L + 2g) × (S + 2e)
- As = Ap × k
- Total As_total = ΣAs_i
FAQ
Should I enter the rafter length?
No. Enter horizontal plan dimensions, not the length of a sloped member.
How does the calculator treat overhang?
By default, overhang is treated as horizontal projection. A shed uses one run-side overhang; a gable uses both eave sides.
Can I use this for hip roofs or valleys?
Yes. Split the roof into rectangles or trapezoids, then sum the sections.
Will degrees and percent return the same result?
Yes, if they describe the same pitch. Use the converted values to confirm.
Important notes
- This tool estimates area. Confirm overlaps, details, and edge conditions separately for actual work.
- For hip roofs, valleys, dormers, and similar geometry, use split sections.
- All dimensions are assumed to be horizontal projections.