Roof Area Calculator
Estimate roof surface area from the building footprint and roof pitch. Enter one or more roof sections and calculate the total area, including an optional allowance for cutting and material waste.
Enter Your Roof Measurements
How the Calculation Works
For a simple roof section with a rectangular horizontal footprint, the footprint is the length multiplied by the width. For a sloped roof, the surface area is estimated using the roof pitch.
Length × Width
Sloped roof area
Footprint ÷ cos(pitch angle)
Area with waste
Roof area × (1 + waste percentage ÷ 100)
Example
A rectangular footprint measuring 10 m by 8 m has a footprint of 80 m². At a 30-degree pitch, the estimated sloped area is approximately 92.38 m². With a 10% waste allowance, the estimated coverage requirement is approximately 101.61 m².
Important limitations
This calculator uses a simplified geometric estimate. Selecting gable or hip roof type does not automatically calculate the separate geometry of individual roof faces. For complex roofs, enter the appropriate individual face dimensions as separate sections. Consult a qualified roofing professional before ordering materials.