It is often compared to slope, but is not exactly the same. Roof pitch is the measurement of a roof's vertical rise divided by its horizontal run.

Although ceramic tile roofs are expensive, they can have a life span of over 100 years. Shingle roofs typically have a life span of 15-30 years, while membrane roofs usually last 5-15 years.

The most common roofing materials used in the United States include shingles, membrane roofing, and ceramic tile, all of which have different life spans. Using the aggregate area of these simple shapes can yield a more accurate roof area to be used with the Roofing Material Calculator. The Area Calculator can be used to calculate the area of a variety of simple shapes that together can comprise the area of the roof. The calculator cannot account for complex shapes based on a measurement of square footage alone.

In cases where a roof has a complex shape, such as in the image to the right, measuring the dimensions and areas of each part of the roof to calculate the total area will result in a more accurate measurement of area. The calculated area is only an estimation.