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How To Measure A Roof (& 3 Things You Should Know)

Posted on November 16, 2023

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How To Measure A Roof (& 3 Things You Should Know)

Whether you’re a homeowner planning a re-roof or a contractor getting ready for your next job, one of the fundamental steps in any roofing project involves accurate roof measurement. This can be confusing, especially if it’s your first time working with shingles and different roof designs. In this article, I’ll guide you through how to measure roofs accurately, including how to calculate square footage. 

Tools and Formulas for Accurately Calculating Roof Square Footage

Your roofing project depends largely on accurate measurements. Proper tools, formulas, and a bit of geometry help make the process straightforward and precise. Measuring the square footage of your roof involves calculating the area for each plane and then adding them together to find the total area.

Tools Needed For Measurement

Your toolkit should consist of necessary items such as:

  1. A reliable tape measure.
  2. A ladder – It must be tall enough to access the roof safely.
  3. Safety gear – This includes harnesses and sturdy footwear to prevent any accidents while you’re on the roof.
  4. A calculator – You’ll need this to add the measurements together and calculate the final area. 

With these tools in hand, you’ll be well equipped to start accurately measuring your roof.

Simple Yet Effective Formulas

Here are some essential formulas needed to calculate roof square footage:

  • For a single rectangular plane: Simply multiply length by width (L x W).
  • For triangular planes: Multiply the base by the height, then divide by two (½ (B x H)).
  • Calculate multiple planes individually and then simply add them together for total square footage.

Remember, when measuring your roof or estimating its size, consider whether it has a uniform structure, like a gable roof, or a complex design, like a hip and valley roof with varying planes. 

Understanding How To Calculate The Square Footage Of A Roof

Before we dive into the roof measurement, it’s essential to understand what square footage is. Square footage refers to the total surface of your roof in square feet. It gives you an idea about the area, helping to estimate the required materials more precisely.

Measuring a roof’s square feet can be slightly tricky due to the irregular shapes and slopes involved. Below are step by step instructions on how do so:

  1. First, divide your roof into geometric sections such as rectangles or triangles. 
  2. Measure the length and width of each rectangle or base and height of each triangle, considering overhangs where necessary.
  3. For rectangular and square sections, multiply the length by width; for triangular ones, multiply the base time height and divide that number by two. 
  4. Lastly, add up all calculated numbers. This will give you the estimated square footage of your roof. 

Keep in mind that this process might require some level of comfort with basic geometry rules.

Step By Step Guide for Measuring a Roof from the Ground

Although there are multiple ways to measure your roof, doing it from the ground is typically the most efficient and safe option. Here’s a simple guide on how you can do it:

  1. Begin by obtaining the basic dimensions of your home, if available, through relevant blueprints or property records. If not available, determine the length and width of the base, which equals the length and width of each wall around your house.
  2. Measure the overhangs, if any, separately. 
  3. By multiplying these lengths and widths together, you’ll obtain an estimated measurement of the roof square feet. 
  4. For pitched roofs, apply a pitch factor (which we will cover later in this article) to get your actual roof surface square footage.

How To Use High Tech Tools Like Apps and Drones

Many people often ask how to measure their roof if they don’t have physical access to it or can’t see it clearly. The answer is technology driven solutions such as measuring apps and drone usage:

Roof Measurement Apps

Various applications available on the market can provide free roof measurements from satellite images. They generally require access to specific data about your property and then produce comprehensive estimations using digital mapping technologies. 


Equipped with advanced cameras, drones are a popular choice for those wanting to measure their roof from the ground. Drones capture your roof details with precision, saving time and ensuring your safety by eliminating the need for ladders or walking on the roof.

Understanding Roof Pitch Factor

Pay close attention to the pitch or slope of the roof. This aspect holds significance as it directly influences not only the amount of roofing material required but also affects drainage and resistance to elements.

The Importance of Determining the Pitch Factor When Measuring a Roof

Taking into account the roof’s pitch factor can make all the difference between efficiently executed roofing work and unnecessary complications down the line. It contributes greatly to how materials are utilized, as under estimating may lead to a shortage, while overestimating results in wastage.

Methods for Measuring Roof Pitch

There are various ways to measure roof pitch, but this is the most common method:

  • Using a Pitch Gauge: Available at most hardware stores, this tool gives a direct reading of your roof’s slope once placed against it. Climb up to your roof and place your gauge steady against any part of it, then note down the measurement shown.

But even with this simplified method on how to measure roof pitch, it’s crucial to always consider your safety. Don’t hesitate to seek professional services that’ll provide free roof measurements.

Common Challenges With Roof Measurement and How to Overcome Them

Finding the dimensions of a basic, rectangular plane of a roof may be straightforward, but complex structures are usually more difficult.

Dealing with Complex Roof Features Like Chimneys, Skylights, and Dormers

Many roofs feature more than just shingles. Components such as chimneys, skylights, and dormers not only enhance the aesthetic appeal but also add layers of complexity when it comes time to measure the roof.

  • Chimneys are vertical elements above your roof. To accurately evaluate its size, measure both its base area (length x width) and its vertical height.
  • Skylights are installed on your rooftop. You’ll need to deduct their area from your total roof area when calculating how much roofing material is needed.
  • Dormers can be a complex to measure, as they can be of any size, shape, and dimension. They can incorporate all three elements: walls (sides), floor (base), and ceiling (roof). Measure each side separately before adding all areas together. 

Remember that correct handling of these features during measurement significantly reduces waste while optimizing material usage.


After diving into the complex world of roof measurements, we have tackled critical topics such as the importance of accurately planning, estimating, and recording the process. Calculating measurement incorrectly could lead to wasted materials, a disrupted project timeline, and unnecessary costs.

Free Roof Inspections For Tulsa Homeowners!

If you are considering installing a new roof or just replacing an old one, you’ll need to measure the roof with precision to avoid costly mistakes. It is always best to leave the roof measuring to professionals.

Contact A. Fricker Roofing & Waterproofing for your roof inspection and measurement in Tulsa, OK. The team of expert roofers, equipped with advanced technology, measurement tools, and the proper knowledge, will assist you in dealing with your roof measurement and installation. Call us today at (918) 402-7167!