How Many Roofing Squares Do I Need for My Roof?

Measuring the Roof

• Measure each segment of the roof individually. Break the roof into geometric shapes of squares, rectangles or triangles. Measure the width and length of each section. The measurements will require working at the edges of the roof. Use a tape measure long enough to accommodate the largest section of the roof.

Calculating the Area

• Calculate the area of the roof using standard mathematical equations. The area of a square or rectangle is found by multiplying the length by the width. Triangles involve multiplying the width by the height and dividing by 2. Add all the areas together for the total area of the roof surface.

Allowing for Waste

• Cutting shingles at rough ends and around chimneys and vents results in some waste. Factor in about a 1 percent waste factor for simple roofs with no valleys and a single ridgeline. Use a 5 percent waste factor for complex roofs with multiple segments, valleys and ridgelines.

Getting the Materials

• While the roofing material is calculated and sold by the square, it isn't delivered that way. Shingles are bundled together in sizes appropriate for handling by a single person. Heavy shingles may require three to five bundles per square, while lighter shingles may be packaged in two or three bundles per square.