How to Measure For Siding: A Step-by-Step Guide

When completing any home improvement project, the old adage still stands: measure twice, cut once. Since siding installation is such a large investment, that rule applies just as much to siding as to any other element of your home. Inaccurate siding measurement can lead to wasted materials, improper fits, or worse. 

However, with accurate measurements, you can ensure that your siding is properly fitted to the sides of your home. It also helps ensure the siding achieves an air- and water-tight seal once it’s installed.

By now, you’re probably wondering how to measure for siding the right way. On top of that, what tools do you need for a proper measurement? We’ll cover everything you need to know below.

How Is Siding Measured?

Siding is measured by square footage. When ordering siding or talking to a construction professional, you may also hear them refer to the “number of squares” that you need. A square is a standard building measurement equal to 100 square feet and is used for siding, roofing, and other materials. 

Tools You’ll Need

You’ll need a basic selection of tools to measure your house for siding:

• A tape measure, preferably 25 feet or longer
• Pen and paper or a digital method to write down numbers
• A calculator
• A ladder to help with measuring higher areas

It may also be worthwhile to grab a friend to help stretch the tape measure over long spans.

How to Measure a House for Siding

Before you order your siding, you’ll first need to measure your home to create an accurate siding estimate. The actual siding measurements should cover the home’s exterior, not including the roof. Any wall that will be sided should be included in your measurements to tally the total square footage. However, elements like gables, dormers, windows, and doors can add complexity, which is why we’ll show you exactly how to measure around each of these areas below.

Measuring Exterior Walls

To measure for home siding, start with a single wall. 

• Measure the height, in feet, of one side, from the base of the siding all the way up to the soffit and fascia. 
• Measure the width of that same wall in feet.
• Be sure to measure only the square or rectangular part of the wall. 
• Write those measurements down for later.

To get the square footage of these sections, simply multiply the length by the height, and write the results down for later.

Measuring Gables and Dormers

Next, it’s time to measure any triangular parts of the wall. 

• Measure from the center of the triangle’s base to the top.
• Next, measure the entire length of the triangle’s base.
• Last, multiply the triangle’s height by half of the triangle’s base length. 

This will give you the square footage of the gabled section of your wall. Note this measurement alongside the square footage of your wall’s square section.

Taking Windows and Doors into Account

If you go by the numbers above, you’ll likely overbuy your siding. To find the exact square footage, you’ll need to calculate the parts of the wall that don’t need siding. These include windows, doors, garage doors, vents, and any other areas not covered by the new siding.

To calculate these, just do the following:

• Measure each element’s height and width. 
• Multiply the height by the width to get the square footage for each element.
• Add up the square footage for each element.
• Subtract this total from the total amount of siding calculated for that entire side of the house. 

This will give you the most accurate picture possible for how much siding you’ll need for each side of your home.

Repeat All the Way Around Your Home

You’re not done yet! Once you’ve calculated the square footage for one exterior wall, the next step is to repeat the process for the rest of your home’s exterior walls. 

Don’t assume that just because some walls may look similar in size and shape, the square footage will be roughly the same. That can lead to over- or under-buying siding by a surprising amount. Be thorough and get unique measurements for each one. 

Once you’ve completed measurements for each wall, add the final totals together to calculate the entire square footage needed for your home’s exterior.

How to Measure For Siding: Calculating Squares

To calculate the squares of siding, divide the total square footage number you arrived at by 100. This will give you the number of squares needed for that side of the house.

Here are some examples of how the math works out:

• A 1,200-sq. ft. exterior would need 12 squares of siding
• A 1,500-sq. ft. exterior would need 15 squares of siding
• A 2,000-sq. ft. exterior would need 20 squares of siding

Calculating the number of squares needed can help you get more accurate pricing information.

Pro-Tip: Order Extra Siding Plus Accessories

You may be thinking that you only need to order exactly as much siding as you calculated. However, as with any building project, it’s always better to have more on hand than you need — not less.

At minimum, add an extra 10% of siding material to your order total to make sure that you have enough on hand to cover miscuts, damaged pieces, and end cuts that can’t be repurposed to fit smaller areas of the home’s exterior. 

If you’re ordering TruLog steel siding or another similar product, don’t forget to account for the accessories you’ll need for installation, too, like trim, starter strips, and J-channels. You may also want to factor in new soffits and fascia, as these are often installed alongside siding to ensure the new siding looks properly finished and has full curb appeal.

Best Practices for Accurate Siding Measurement

Siding is a big investment — and mistakes can lead to delays and cost overruns if you end up ordering more siding later. To ensure your project proceeds as smoothly as possible, keep these best practices in mind.

• Measure each side individually: Even if it looks similar in size to the other sides, a foot or two difference can lead to large discrepancies.
• Measure windows, doors, and other elements individually: This creates the most accurate numbers possible.
• Add at least 10% extra: Account for scrap and minor miscalculations by padding your final number.
• Don’t forget accessories: Measure for trim, J-channels, starter strips, and other accessories, and make sure these measurements are in linear feet, not square feet.
• Measure twice: Double-check your numbers before doing your calculations to ensure accuracy.
• Treat triangular areas separately: Measure gables and similar areas separately rather than as part of a rectangle to avoid overestimating your square footage.

If you follow all of the steps above and implement these best practices, it’ll be easy to get an accurate idea of how much siding you’ll need to order.

Discover Great Siding That Lasts

Now that you know how to measure for siding, you can get an accurate picture of how much siding you need. The next step is choosing a great product for your siding project — not all materials are created equal.

If you’re looking for an option that delivers extreme durability, low maintenance, and a long lifespan, TruLog steel siding may be the answer. Learn more by using our Visualizer tool, where you can see how each of our siding colors and styles will look on your home.