How Many Shingles Do I Need? (Roofing Calculation Guide)

By Amanda Lutz Updated February 6, 2024

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Shingles are one of the most popular roofing materials in the country. To determine the total cost of a shingle roof replacement, you’ll first need to estimate how many shingles you need. We’ll explain how to measure and calculate your roof’s surface area and pitch to figure out how many shingle bundles you need to buy for your project.

 


 

How to Calculate the Area of Your Roof

Your roof’s square footage will be larger than your home’s square footage to account for overhangs, dormers, and other features. For this calculation, measure the height and width of each plane—that is, each flat surface on the roof that’s covered in shingles. We recommend first making a simple diagram of your roof. As you measure, fill in the roof dimensions on the appropriate part of the diagram to ensure you don’t miss any spots.

Practice good ladder and roof safety as you measure. For height measurements, stand at the roof peak and advance your tape measure down to the roof edge. For width measurements, measure along the eaves from one edge or ridge to another. You’ll also want to measure any nonshingled surfaces such as chimneys or vents; you’ll subtract these out of the final measurements. The simplest roofs, gable roofs, have only two rectangular planes, but hip roofs and other styles may have triangular or trapezoidal planes.

Here are the measurements you’ll need for each plane shape and how to calculate each surface area.

Once you have the square footage of the individual planes, including dormers, add them to get the total surface area of the roof. Subtract the area of nonshingled surfaces to find the square footage of the roof that needs to be covered in shingles.

 


 

How to Calculate the Pitch of Your Roof

Roof pitch, also called roof slope, determines how much the shingles should overlap. Steep roofs will require slightly more shingles, so calculating pitch will give you a multiplier to adjust your square footage. You won’t need the same multiplier to buy underlayment or other roofing materials. Note that pitch is expressed as a ratio of vertical rise to horizontal run, so a pitch of 6:12 indicates that a roof rises six inches in height for every 12 inches of roof length.

To measure your roof’s pitch, use a level that’s at least 12 inches long and a tape measure. Follow these instructions to find your roof’s pitch.

  1. On your roof, rest one end of the level against the shingles and adjust the other end until the level is perfectly horizontal.
  2. Use your tape measure to measure the distance from the roof’s surface to the 12-inch mark on the level. Round this to the nearest whole number; it will serve as the rise, and the run is 12.
  3. Find the appropriate multiplier on the table below and use it to adjust the total roof area for pitch.
Roof SlopeMultiplier

3:12

1.031

4:12

1.054

5:12

1.083

6:12

1.118

7:12

1.158

8:12

1.202

9:12

1.25

For example, if your roof is 2,186 square feet and has a pitch of 5:12, you would multiply 2,186 by 1.083 to get an adjusted total of 2,368 square feet. Shingles and other materials are sometimes measured by the roofing square, which is an area of 100 square feet. You can divide the total by 100 to get the number of roofing squares you need to cover; 2,368 square feet is equivalent to 23.68 squares of shingles.

 


 

How to Choose the Type of Shingles for Your Roof

Shingles are a good choice for nearly all roof sizes and shapes aside from flat roofs. Although asphalt shingles are the most common, you can choose from many materials at different price points.

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Just answer a few questions, and we’ll take care of the rest!

 


 

How to Estimate the Number of Shingles You Need

Once you’ve chosen the type of shingle you want, you can use your pitch-adjusted square footage to calculate the number of bundles to buy. All types of shingles come in bundles that cover approximately 33 square feet of roof. That’s three bundles for every roofing square. Take the number of squares you calculated above—in our example, 23.68—and round that number, then multiply by three to get 72 shingle bundles.

When making your calculations, plan for some overage in case of wasted shingles. Some shingles will need to be cut to shape or used as valley or ridge caps, and a few shingles may arrive cracked or unusable. Plan for about 15% wastage, so multiply the number of bundles by 1.15 to get the final number of shingles you need. In our example, 72 x 1.15 = 82.8 rounded to 83. To cover a roof of 2,186 square feet and a pitch of 5:12, you’ll need a total of 83 shingle bundles. Use an online shingle calculator to help with this math if you get stuck.

 


 

How to Hire a Professional

You can measure your roof and calculate the amount of material yourself, but your actual roofing project should be completed by a licensed professional. A pro can also assist with measuring and calculating the roofing materials you need. Here’s what to look for when hiring a roofing contractor.

 


 

Our Recommendation

Roofing a house is a substantial financial investment. To estimate your total price, you’ll need to calculate how many shingles you need to cover your roof. Use the steps and formulas provided above to find your roof’s square footage and pitch to estimate the number of bundles you’ll need to buy. A professional roofing contractor can also assist you with these calculations.

Compare Quotes from Roofing Specialists
Just answer a few questions, and we’ll take care of the rest!

 


 

Shingles FAQ

How much does a new roof cost?

The cost of installing a new roof is usually between $5,700 and $12,500.

How long do shingles last?

Basic three-tab asphalt shingles usually last 15–20 years, while premium architectural shingles can last up to 30 years when well-maintained.

How do I know if I need a new roof?

If your current shingles are cracking, curling, or missing granules, it may be time for a new roof. Mold, moss, algae streaks, and sagging are also signs that you need a new roof. Additionally, consider replacing your asphalt shingle roof if it’s 20 years old or more.

How do I prevent shingles from curling or cracking?

The first step to preventing shingles from curling or cracking is installing them properly. After they’re installed, make sure your roof is properly ventilated to prevent heat from building and curling the shingles.