Roofing Calculator
Calculate roof area, squares, and shingles needed for your roofing project.
Roof Dimensions
What is the Roofing Calculator?
The Roofing Calculator is an architectural estimation tool that helps homeowners and contractors calculate the true surface area of a sloped roof. This allows you to estimate exactly how many bundles of shingles or metal panels you need to buy.
How It Works (Formula)
Because roofs are pitched (angled), their surface area is larger than the flat footprint of the house. The calculator applies a geometric "pitch multiplier" (derived from the Pythagorean theorem) to the flat footprint area to find the true hypotenuse area.
$$ \text{Roof Area} = \text{Base Area} \times \text{Pitch Multiplier} $$
Roofing materials are sold in "Squares", where 1 Square = 100 sq ft.
How to Use It
Enter the base length and width of the house footprint. Then, select the roof's pitch (e.g., 4/12 or 6/12 slope). The calculator will output the true square footage of the roof and tell you how many "Squares" of shingles to order.