Roofing Calculator
Estimate roof surface area from footprint and pitch in roofing squares and sq ft.
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Result
Formula
Factor = √(12² + pitch²) ÷ 12; area = footprint × factor.
About this calculator
Estimate the total roof surface area of a simple gable or shed roof from the building's rectangular footprint and roof pitch, expressed in square feet and roofing squares (1 square = 100 sq ft). The calculator assumes a simple gable or shed roof that covers a rectangular building footprint.
How to use
- 1
Enter the building length and width in feet.
- 2
Input the roof pitch as rise per 12 inches (e.g., 6 for 6/12).
- 3
Read the roof surface area in square feet and roofing squares.
Frequently asked questions
What is a roofing square?
A roofing square is a unit of area equal to 100 square feet. Roofing materials are often sold by the square, so knowing the total squares helps estimate the amount of shingles needed.
How do I measure roof pitch?
Roof pitch is the vertical rise in inches over a horizontal run of 12 inches. For example, a 6/12 pitch means the roof rises 6 inches for every 12 inches of horizontal run. You can measure it with a level and a tape measure.
Does this calculator account for overhangs?
No, it assumes the roof area equals the building footprint. If your roof has eaves or overhangs, you should add the extra area manually or measure the actual roof dimensions.
Please note: Results are estimates for general information only and are not professional or medical/financial advice.