Roofing Calculator

Nominal Roof Size (sq. ft.)
Roof Pitch

Tip - Calculate Roof Size:To calculate the size of the roof, you need to measure the size of the roof as if it were flat, account for roof pitch, calculate square footage, resulting in how many squares of material is required.

Start by measuring the length and width of the roof in feet, as you are standing on the ground. Remember that the length and width need to be found for the roof, not the house, so take into account that the roof overhangs the building. Then determine the area of the roof as if it were flat. This can be done by multiplying the length in feet by the width in feet to get the area measurement.

Tip - Calculate Pitch:To accurately calculate the area of your roof, you must first determine its slope, or pitch. Roof pitches are described in terms of rise and run. The run is the distance from the outside edge of a perimeter stud wall to the center of the house. The rise is the distance from the top of a stud wall to the peak of the roof.

A roof’s pitch is determined by how much it rises for every foot it runs. Thus, a moderate 6 in 12 roof pitch means the roof rises 6 inches for every 12 horizontal inches it runs. A 12 in 12 pitch is a steep, 45-degree angle roof.

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