How to Measure a Roof for Shingles

The amount of shingles you’ll need to overhaul your roof hinges entirely on factors specific to it— namely, its size. Since nobody wants to run out to get more shingles, or even worse, order more shingles and wait days to complete the project, it’s important to measure accurately. This way, you can ensure you get enough shingles to get the job done (without having a giant pile of leftover shingles).

So, how do you determine how many shingles you’ll need? It’s a pretty simple process. Here’s how to measure your roof for shingles. 

Safety Considerations

To accurately measure your roof for shingles, you’ll need to climb up there. If you’re not careful and don’t take the proper precautions, you could seriously injure yourself. So, to stay safe, use a sturdy ladder to climb on the roof. If you can’t secure the top of the ladder to the roof, have an adult hold the ladder at the bottom while climbing up or down.

Once you climb to the top, be careful not to lose your balance when moving from the ladder to the roof. Pay attention to any bumps and divots in the roof. Be sure to wear close-toed shoes with plenty of grip to ensure you don’t lose traction as you walk on the roof. 

Additionally, investing in a safety harness is a good idea, especially if you regularly climb up on your roof to complete various tasks. It can make a world of difference in preventing falls that can result in serious injuries.

If you’re uncomfortable or confident climbing onto your roof to measure for shingles, enlist the help of a roofing professional. They have the safety equipment, tools, and knowledge necessary to accurately measure your roof. They can even install the new shingles, saving you the trouble of climbing up there altogether!  

5 Steps of Measuring Your Roof for Shingles

Measuring a roof for shingles is a fairly straightforward task that doesn’t take too long. Here’s how to do it:

Gather Your Tools (H3) 

First things first, gather everything you’ll need to complete the project. You’ll need:

• A sturdy ladder
• Safety harness
• Close-toed shoes
• Measuring tape
• Pad of paper
• Pencil
• Calculator 

Draw a Diagram and Pick a Day (H3) 

If you have a more complicated roof layout or one with multiple planes, it can be easy to forget to measure certain planes, especially the smaller ones. So, before you climb up there, draw a basic diagram of your roof. This way, you can write the measurements of each plane in its designated spot, ensuring you don’t miss any spots. 

Once your diagram is ready, pick a nice, sunny day. Avoid days with any inclement weather, such as rain, sleet, or snow, as climbing up on your roof can be dangerous. 

When you’re ready to climb onto your roof, tuck your paper, pencil, and measuring tape into a pocket or small carrying bag to ensure you have it when you need it. 

Measure the Roof (H3) 

Climb onto your roof using the safety harness for fall prevention if you’d like. Once you’re up there, start measuring each plane. Measure the height and width of each surface. 

Extend your measuring tape from the roof’s peak to the edge of your roof to measure the height. Don’t walk down to or sit at the edge of your roof—this can be very dangerous. Instead, stretch the tape from the lower edge of your roof to the parallel peak above. 

To measure the width, extend the tape from one edge to the other, ensuring the tape remains parallel to the roof’s peak. As you go, take note of each measurement, marking it on the correlating plane of your roofing diagram. 

If your roof has different shapes–not just rectangles–adjust your measuring accordingly. For example, if your roof has a triangle, make sure you measure the length of the triangle’s base and its height. Or, if your roof has a trapezoid, measure the length of each parallel edge and the height of the shape. 

Do the Math (H3) 

After you finish measuring, safely climb down from the roof to use your math skills and calculate the roof’s square footage. Calculate the roof’s square footage by multiplying each rectangle’s width and height and adding them together. 

For roofs with triangles, multiply the triangle base by the height and divide by two. For trapezoids, add the top edge and bottom edge values, multiply them by the height, and divide by two. 

Your equations will look like this:

• Square or rectangle: length x height
• Triangle: (base x height) / 2
• Trapezoid: [(top edge + bottom edge) x height] / 2 

Once you calculate the square footage of each plane, add them together to get the total square footage of your roof.

Determine How Many Shingles You’ll Need (H3) 

With your number in hand, you can determine how many shingles you’ll need for your roofing project. To do that, you’ll need to figure out how many roofing squares your roof consists of. 

A standard roofing square is a 10×10 foot area of your roof, a total of 100 square feet. For example, let’s say you have a 1,972-square-foot roof. Divide that number by 100, and you get the number of roofing squares, which, in this case, is 19.72. To keep things simple, round to the nearest whole number: 20. 

Use that number to determine how many bundles of shingles you’ll need. A standard bundle usually covers about a third of a roofing square, so multiply your number by three to get your answer. In this example, we’d multiply 20 by three to get 60, meaning we need 60 bundles of shingles to complete this roof. 

Of course, since nobody wants to end up with too few shingles, it’s a good idea to have about 10% more than you need. This way, you won’t be left with too few shingles after you have to slice some to fit around the features on your roof. So, in this case, we’d want to buy at least 66 bundles of shingles to ensure we have plenty to complete the job. 

Measuring a Roof for Shingles: In a Nutshell

Measuring a roof for shingles isn’t too tricky. Once you have your numbers, you can easily calculate the square footage of the roof and use that to determine the number of shingle bundles you’ll need. However, if the prospect of meandering around on your roof to measure it doesn’t sound particularly appealing, or you’re not too keen on DIYing your new roof, contact a roofing professional near you. 

Roofing pros are seasoned experts in measuring a roof for shingles and installing them, so you won’t have to sweat the details. Of course, you can always DIY the project, too, if that works better for you, but our roofing pros at Glick’s Exteriors are here to help!