How to Measure Gutters for Your Home in 5 Steps

A visual guide to help you measure and calculate what gutter size you need for your home, simplified in an easy to follow 5-step process.

Adam Graham
May 2, 2022
·
3 min read

There are a few aspects to think about when it comes to installing gutters for your home. And while you may have already decided on the material, shape and color, one vital step in the process is making sure you have the correct gutter measurements. In order for your gutters to work properly, they need to be sized to your home. Rain gutters are available in various widths. They start at around 3 inches and increase up until 6 or 7 inches. For the majority of homes, a depth of 4 to 6 inches is adequate, but some houses may need larger gutters if they are located in an area with high rainfall levels.

5 step guide with explanatory graphics and tables for how to measure gutters for your home

To make this process simpler, we have created a 5-step guide to ensure you get the correct sized gutter for your home. In the above graphic, you can see the necessary steps, and below we break down and explain each step in more detail. Assuming that your area has an average amount of rainfall, you can use these calculations to determine the average size of gutters you need. Follow the five steps below to find out how to measure gutters for your home.

1. Calculate Your Roof Square Footage

iagram and calculations explaining how to calculate roof square footage

The first step when it comes to measuring gutters for your home is to calculate the square footage of your roof. To do this, you need to measure the length and width of each section of roofing that you will attach the gutters to. Then multiply the length by the width to get a total for each section. Add the totals of all of the sections together and this final number is your roof’s square footage. You will need this number again in step 4.

2. Get the Pitch of Your Roof

Illustration of a roof showing how to measure pitch

The next step is to get your roof’s pitch. The pitch is how much the roof slants for every horizontal run of 12 inches. To get your roof’s pitch, you need a level and a measuring tape. Place the level horizontally so that one end is touching the roof. As shown in the graphic above, use the level to measure a straight, horizontal line out 12 inches from where the level touches the roof. From that 12 inch point, measure down to the roof. Whatever this final measurement number is, is your roof’s pitch.

3. Convert Your Roof Pitch Into a Multiplier

A two-column table of roof pitch measurements and the corresponding multiplier

In order to determine the volume of water that your gutters need to hold, there is a simple calculation you must make. Firstly, the graphic above shows you what multiplier you have to use determined by your pitch. For example, if your roof’s pitch (from step 2) is between 4 and 5 inches, your multiplier would be 1.05. You will then use this number in step number 4.

4. Multiply Your Roof Square Footage by the Multiplier

A calculation of roof square footage multiplied by the necessary multiplier

Once you have your multiplier from step 3, use this number and multiply it by your roof square footage obtained in step 1. This resulting number will be what determines the correct size gutter you need for your home.

5. Check Your Result to See What Gutter Size You Need

A two-column table showing calculation results and the corresponding necessary gutter size

 If your resulting figure from the calculation in step 4 falls between 3,500 and 5,500, you can use 4-inch gutters. Between 5,520 to 7,500, you need 5-inch gutters, while 7,500 and above should use 6-inch to 7-inch gutters depending on rainfall.

Trust the Experts

Measuring your gutters for your home can be tricky for many homeowners. The safest and most reliable option is to ask your installer for help, especially if you are unsure or your home has a particularly complicated roof shape to measure. The steps featured will hopefully help you in getting the most accurate gutter size for your home, but it is always advisable to get a second opinion from an expert to make sure the job is done correctly before ordering materials. 

It is also wise to keep in mind that there are other variables that will affect gutter installation. One major factor is the climate you live in, and the amount of annual rainfall in your local area. Be sure to ask your contractor about this before installation gets underway. 

Author:
Adam Graham is an industry analyst at Fixr.com. He analyzes and writes about the real estate and home construction industries, covering a range of associated topics. He has been featured in publications such as Better Homes and Gardens and The Boston Globe, and written for various outlets including the National Association of Realtors, and Insurance News Net Magazine.

References

  • Thomson Creek “What Is the Standard Gutter Size?”
  • This Old House “How to Size Gutters and Downspouts”