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How to Measure a Roof for Shingles

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Whether you’re re-roofing your home or purchasing shingles for a brand-new house, it’s important to understand that a successful roofing project often requires a significant investment of both time and money. As you begin shopping for materials, you might wonder how to measure a roof for shingles. After all, roofing materials vary greatly in cost and are priced per square foot. To determine the size of your roof, contact a professional roofer who can measure your roof and provide an estimate for the roofing project.

How to Measure a Roof for Shingles

Don’t worry too much if you don’t know how to measure a roof for shingles. Your roofer will measure the surface of your roof to determine the total square footage, which will dictate how many shingles must be purchased to fully cover the roof’s planes.

But if you’re curious how the measuring process works, think back to your geometry classes in school. To calculate a rough estimate, follow these steps:

  1. First, you must measure the length and width of each plane of the roof, including dormers. If the planes aren’t rectangles, this may be complicated.
  2. Next, to calculate the square footage of each rectangular plane, multiply the length by the width. For example, if a plane is 130 feet long and 100 feet wide, it’s 13,000 square feet.
  3. Finally, add together the square footage of each plane to calculate the total square footage of the roof. So if there are two planes that both measure 13,000 square feet, the total square footage of the roof is 26,000 square feet.

Roof surfaces are measured in “squares,” with each square being 100 square feet. So if your roof is 26,000 square feet, you’ll need 260 squares to coat it.

As you’re making your calculations and shopping for materials, remember that you’ll need to purchase slightly more shingles than you think you’ll need based on the total square footage. If you order enough shingles to coat the roof exactly, you won’t have enough. Remember that you’ll likely need shingles to cap hips and ridges of the roof and starter shingles to place along the eaves and rakes. Some shingles will also be cut for the installation, and while some of these fragments can work as starter shingles, smaller bits will be tossed out. Your roofer can tell you how many extra shingles are required for the project.


A new roof also requires the purchase of underlayment, which is a water-resistant or waterproof barrier material adhered directly to the roof deck, under your chosen roofing materials. The underlayment provides an additional layer of protection against severe weather. If you purchase 26,000 square feet of shingles, you will need to purchase a matching 26,000 square feet of underlayment for protection. However, if this is a re-roofing project, the new shingles may be applied directly over the existing roof.


Climbing around on a roof is not safe, so we do not recommend measuring the planes of your roof yourself. Plus, it is important that the measurement is accurate if it will be used to purchase roofing materials. So instead of going to the trouble yourself, contact a reliable roofer for an estimate. The roofer can use professional tools and methods to measure your roof and calculate the total square footage, and then provide estimates for shingles, underlayment, and other materials based on that total.

Are you ready to get started? Taylor-Made Roofing is here to help. As a family-owned company with more than 20 years of experience meeting the roofing needs of those who live and work in southern Missouri, we know how to spot a roof in need of repair and repair it quickly, efficiently, and affordably. Whether you’re in need of basic maintenance, a repair, or a total replacement, we’re ready to help. Contact us today to learn more.

Fully licensed and insured, Taylor-Made Roofing is ready to take care of your roof.
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