Roof Area Calculator
Calculate roof area from footprint and pitch
Estimate a roof's surface area from the building footprint and the roof pitch. Useful for ordering roofing materials.
Calculate roof surface area from the building footprint and roof pitch (rise per 12" run).
Roof Area
1341.6
sq ft
Roofing Squares
13.4
1 square = 100 sq ft
How to Use This Calculator
- Enter the building length and width.
- Enter the roof pitch (the rise per 12 inches of run).
- Choose the roof type (gable or hip).
- Review the roof area and the number of roofing squares.
Why Use This Calculator?
- Estimating roofing material before getting quotes.
- Comparing how pitch changes the surface area.
- Converting area to "squares" for ordering.
Real-World Examples
A 40 × 30 ft building, 6:12 pitch
With a pitch factor of about 1.12, the roof surface is around 1,340 square feet — about 13.4 squares of roofing.
What's a roofing square?
A roofing square covers 100 square feet. Roofing material is often sold by the square, so the calculator divides the surface area by 100.
Frequently Asked Questions
What's the pitch factor?
A sloped roof has more surface than the flat footprint below it. The pitch factor (based on rise per 12 inches of run) accounts for that extra area.
Is a hip roof different from a gable?
Slightly. A hip roof slopes on all four sides; a gable has two sloped sides. Both add area over the footprint, just in different shapes.
Does this include overhangs?
Not unless you add them to the building dimensions. Real roofs usually overhang the walls, which adds area.
Important Disclaimer
Estimates based on simple rectangular footprints and uniform pitch. Real roofs have overhangs, valleys, dormers, and varying pitches that change the actual area. Verify before ordering materials.
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