Roofing Calculators

Roofing Area Calculator

How to use our free roofing area calculator

Step #1: Calculate the house base area The house base area represents what the area of the roof would measure in square feet if it was laid flat on the ground, giving you the width and length of the entire area. Step #2: Find the total roof area based on roof pitch The roof pitch, or roof slope, must be measured as a ratio between the roof’s vertical rise and its horizontal run. Common roof pitches range from 4/12 to 9/12. Step #3: Estimate roofing materials needed Once you calculate the total roof area and roof pitch, you can estimate the roofing materials needed to construct a new roof.

How can I estimate the size of a roof?

While the ServiceTitan Roofing Calculator includes a cost calculator below, roofers must first estimate the size of the roof to know the amount of materials to order before providing an accurate estimate. Below, we walk through each step required to estimate the size of a roof. Generally, asphalt shingles are the most common and economical roofing materials, while metal roofs cost more but require less maintenance.

Step #1: Calculate the house base area

Measure the surface area of the house in square feet. If the home is rectangular, simply measure around the entire perimeter. For homes with more complex shapes—such as a gable roof (flat-faced end with an A shape), hip roof (four sloping sides, without a flat face), or one with dormers, eaves, or skylights—measure the area of each shape individually and aggregate for more accurate results.

Step #2: Find the total roof area based on roof pitch

The roof pitch, or roof slope, must be measured as a ratio between the roof’s vertical rise and its horizontal run. Common roof pitches range from 4/12 to 9/12.

Step #3: Estimate roofing materials needed

Once you calculate the total roof area and roof pitch, you can estimate the roofing materials needed to construct a new roof.

Roof pitch multipliers

Roof pitch multipliers help to simplify the process of measuring the total surface area of your roof. The multipliers are determined based on the ratio of the rafter to the run. This number corresponds to roof pitch and is multiplied by the horizontal area measurement to determine the actual area of the roof. Below, find a table of these multipliers and angles used to determine roof pitch.

*Disclaimer: the ServiceTitan Roofing Calculators are solely meant to be an estimation. Roofs may have different or more complex shapes which aren’t reflected in this calculator. If you are looking for a more definitive estimation, please consult a professional.