How to Measure For Siding

Construction professional drawing a marking line with a pencil on a piece of brown siding.

When undergoing any construction project, the old adage stands: measure twice, cut once. This is as true for siding as it is for any other element of your home.

Improper siding measurement may lead to wasted materials, improper fits, or worse. But with proper measurement, you can ensure your siding is properly fitted to your home. You can also ensure an air and water-tight seal once it’s installed.

Clearly, siding measurement is a critical first step when installing siding or when re-siding. But how is siding measured? And what tools are needed for a proper measure? Join us in our full siding measurement explainer. Read on to learn more.

How is Siding Measured?

When ordering siding or when talking with a construction professional, you may hear them refer to a square. Siding is measured using a standard building measurement: squares. One square is equal to 100 square feet.

How to Measure a House for Siding

Before you order your siding, you’ll first need to measure your home. Specifically, you will need to measure your home’s exterior (not including the roof). What you are looking to calculate here is the total square footage of your home’s exterior walls. Any wall that will be sided should be included in your measurement.

Measuring Exterior Walls

To measure your home’s exterior, start with a single wall. Measure the height, in feet, of one side. Now, measure the width of that same wall in feet.

While measuring, be sure to only measure the square or the rectangular part of the wall. Note those measurement down for later.

Measuring Gables and Dormers

Next, it’s time to measure the triangular part of the wall. To do this, measure starting at the base of the triangle. Bring your measurement all the way up to the top of the triangle.

Next, you’ll need to measure the base of the triangle.

Lastly, you’ll multiply your triangle’s height by half of the triangle’s base length. With this number in hand, you’ve measured the square footage of the gabled section of your wall. Note this measurement alongside the square footage of your wall’s square section.

But we’re not done yet…

Taking Windows and Doors into Account

If you simply go by the numbers above, you’ll likely overbuy your siding. To find the square footage exactly, you’ll need to calculate the parts of the wall that won’t need siding.

This could include:

  • Windows
  • Doors
  • Vents
  • And more.

Simply measure each element’s height and width. Multiply the height by the width for each element, one by one. Then, add them all up.

The next step is obvious: subtract the number above from the square footage you calculated for the entire side.

Lastly, divide the number above by 100. When done properly, you will have calculated your home’s square footage for one exterior wall.

Repeat Three More Times

Obviously, the steps above only account for a single wall in your home. To calculate your home’s overall exterior square footage, you’ll need to measure all four exterior walls. But remember: unique measurements per side are recommended.

Once you have all four walls measured, simply add all four numbers together. With that, you’ll have your home’s entire exterior square footage calculated.

How to Measure Siding: A Calculation

Now that you know your square footage, you can calculate how much siding you’ll need. Since we know a square of siding is equal to 100 square feet of material, the calculation is easy. Simply move the decimal places two spaces to the left.


  • A 1,200-square-foot house would need 12 squares of siding
  • A 1,500-square-foot house would need 15 squares of siding
  • A 2,000-square-foot house would need 20 squares of siding
  • Etc.

Pro-Tip: Order Extra Siding

You may be tempted to order exactly as much siding as is needed per your calculation. However, like any building project, it’s always better to have more than you need than less.

We suggest ordering what you need to cover your calculated square footage plus 10% extra for mistakes.

Discover Great Siding that Lasts

Accurately measuring is only half the battle when it comes to a siding project. The other half lies in what material you choose. And not all types of siding materials are created equal.

At TruLog Siding, we craft wood-look steel siding that is built to last. Our siding is easy to install, affordable, and gorgeous. And it can instantly transform nearly any home’s aesthetic. Get an estimate today.

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