What A Roofing Square Is & How To Calculate It

What a Roofing Square Is & How to Calculate It

By Angelina Zhuravleva  •  September 14, 2022  •  5 min
What a Roofing Square Is & How to Calculate It

Simple Method For Measuring Roofing Squares 

When homeowners plan a roofing project, they need to become familiar with specific industry terms. One is a "roofing square," which roofers use to calculate the material required to complete the job. So we've prepared this guide to help you measure the square footage of your roof, figure out what a roofing square is, and how to calculate it.

What Are Roofing Squares? 

A roofing square is a unit of measurement used to calculate the area of a roof. When contacting a contractor, the number of squares on your roof replacement project can help you get an accurate estimation of the cost of your roof replacement project. 

How to Calculate the Square Footage of the Roof 

To calculate roofing squares, you must determine your roof's total area. The roof's square footage will differ from the house's square footage because nearly 100% of roofs are built at an angle, while foundations are flat surfaces.
To measure a roof footprint, you should measure its overall dimensions. You will need to gauge the length and width of each part and then multiply those numbers to determine the square footage. Once you have that figure, you can calculate roofing squares.

Safety is a Top Priority! 

But first, ensure you wear shoes with grippy soles when working on the roof, and avoid wearing clothes with loose or dangling material. Never leave your ladder unattended, and ensure it is always adequately secured.

Also, never go up on the roof for measurements when your roof is wet. The surface of a wet roof can become dangerously slippery, especially if it is old and covered with debris.  

Roof Measurement Tools 

Small roofs can be measured using a tape measure; larger roofs may require a measuring wheel. If your roof is inaccessible, you may use satellite software such as iRoofing or EagleView. 

And Here is How You Measure Your Roof 

For example, we will use Rox Roofing's excellent video to demonstrate how to calculate roofing squares.

To calculate the roof area, follow these steps: 

Sketch of the roof to calculate roofing squares
  1. As demonstrated in the video, sketch your roof. 
  2. Determine the dimensions of any chimneys in your home (if applicable).In our example, we have a 40' x 40 chimney. Since it is not a large area, we will not deduct it from the total square footage of the roof. However, if the chimney was larger (e.g., 160 sq ft), we would remove it from our calculation.       
  3. Then we'll measure each roof side from the eave to the ridge. In our example, it's 22 feet. 
  4. Then we'll measure the length of a ridge from one edge down to another. In our example, it's 34 feet. We'll repeat for each part of the roof.
  5. Now let's calculate the roof's total square footage by multiplying each part's length by width.
    We will multiply 22' x 34', giving us 748 sq ft. We just round it up to 750 square feet for both areas.

This area is 18 feet by 10 feet, which gives us 180 square feet. This roof has four separate areas that we measured individually.
To determine the total square footage of this roof, we must add all these areas together. The total square footage of this roof will be 180 + 180 + 750 + 750 = 1860 sq ft. To double-check our calculation, we'll run these numbers twice, just in case. And that's how we get a total square foot of the roof. Pretty simple, isn't it?

How to Calculate Roofing Squares 

Once we have measured the roof and determined the square footage, it is time to convert this number into roofing squares. Here is the simple formula: 100 sqft = 1 roofing square. 

So, all you need is to divide the total square footage of your roof by 100. In this case, it's going to be 18.60 roofing squares. 1860 divided by 100 gives us 18.6 roofing squares.

How Many Roofing Squares in 1200 & 2000 Square Feet Roofs 

We'll give you two more examples of the most common roof sizes in the US to ensure we've covered all our bases.
For example, if your roof has 1200 square feet of surface area, you have 12 roofing squares. If it has a surface area of 2000 square feet, you will have 20 roofing squares. The number of roofing squares will help you and a contractor estimate your roofing project. 

The Waste Factor Adds to Roofing Squares 

When calculating the materials needed for a roofing project, adding 10-15 percent to your total squares is customary. So, if we have 18.6 roofing squares, we'll multiply that number by 1.15 to ensure we have enough materials. 

Get a Written Estimate 

After determining your roofing squares and giving this number to a roofer, you can get a written estimation. They will still need to figure out all the hips, ridges, starter strips, and everything else. But knowing how many roofing squares and having a sketch like in the example from Rox Roofing, you can be sure that you'll get a more accurate estimation.
Note that it won't be the final estimation. A roofer needs to inspect your roof, ventilation system, shingle layers, accessibility of the roof, and other factors before giving you an estimate for replacing your roof. To learn more about the cost of a new roof and what can drive the price up, read our article "How much does it cost to replace your Roof in 2022". 

Directorii Helps Homeowners Find The Best Professionals 

Directorii is the best-trusted service for homeowners, matching them with top roofing specialists nearby. Begin your search by selecting the type of service you need and your city to get a list of high-rated, reliable roofing professionals near you.

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