Roofing Calculator
Estimate roof surface area and roofing squares for a simple gable roof.
How to Use the Roofing Calculator
Enter the building dimensions and roof pitch information to estimate roof area and roofing squares.
Practical Example
A simple 10 m by 8 m footprint has 80 m² of horizontal area. The actual roof area is higher once roof slope is included.
Factors That Affect the Result
Pitch, roof shape, overhangs, valleys, hips, dormers, waste and local installation practices can increase material requirements.
Frequently Asked Questions
What is a roofing square?
It is a common roofing unit equal to 100 square feet.
Does roof pitch change area?
Yes. Steeper roofs have more surface area than the horizontal footprint.
Should I add waste?
Yes. Complex roofs typically need a larger waste allowance.
Related Tools
Roofing Material Estimation
Roofing calculations depend on roof area rather than the building’s floor area. Pitch increases the actual surface that must be covered, and valleys, hips, ridges and cut pieces add waste. Roofing materials are often sold in squares or bundles, so round the estimate to the supplier’s package size. Add an allowance for trimming and replacement pieces, especially on complex roofs, and confirm underlayment, flashing and ridge materials separately.