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Calculate the surface area of your roof

How to calculate the roof area from
house area and pitch

Roof area calculator
In this article, we will talk about calculating the roof surface starting from

- Roof incline (pitch US )
- House surface (plus the area with which the roof extends outside the house - it can be calculated by multiplying the extension with the perimeter of the house).

How to calculate Roof surface

For a roof incline of (pitch x/12):
You dont know the pitch?
Use our calculators
We find the slope factor from pitch:
Slope factor = (hypothenuse of rise 4 and run 12) / 12
We find the hypothenuse using Pythagorean theorem:
hypothenuse² = 4² + 12² = 160
Hypothenuse is therefor squared root of 160:
hypothenuse = root of 160 = 12.65
Slope factor is hypothenuse divided by 12:
slope factor = 12.65 / 12 = 1.0541
Surface of the roof = house surface x slope factor:
x 1.0541 = 210.82
Total roof surface = 50

This formula for calculating the roof surface produces approximate results! The resulted surface area is similar with that of a gabled roof, but other roof shapes might have a very different surface area!
One advantage of this formula is that it can be used as an approximation for houses with unique shapes or with complicated roofs - we can use it to obtain a very general idea about the roof surface.
Please check our roof shape calculators - if we have a calculator for your roof shape, it is going to produce pretty accurate results. .