A Guide on How to Choose the Right Gutter Size for Your Home

Choosing the right gutter size ensures your gutters funnel rainwater away from your home. This will prevent overflowing during heavy rainfall or storms. Several factors are to consider, including your roof pitch factor and rainfall intensity. Calculating the adjusted square footage is also important to determine the proper gutter size.

Roof Pitch

There’s no doubt that gutter systems play a critical role in managing the flow of rainwater around a home. The gutter system’s size and capacity directly impact its ability to funnel rainwater off the roof and into downspouts without overflowing or clogging. Knowing your roof pitch is critical for determining the proper gutter size for your gutter installation Oregon City. A steeper slope requires a larger gutter to accommodate the increased speed of water run-off. A hipped roof also needs a different gutter size to ensure the system can handle the entire effective area. The most accurate method to determine the correct gutter size involves climbing a ladder and measuring from the ground. However, this can be dangerous and is not recommended for those afraid of heights. The next best option is to use a gutter sizing chart to find the correct gutter size for your roof. These tables will take the guesswork out of the process and help you to make an informed decision based on your local rainfall density.

Rainfall Intensity

While many homeowners will find that standard five or 6-inch gutters are an excellent fit for their homes, others may want to consider more extensive options. The width of the gutter trough sizes gutters, and each size carries a different capacity. You can find the maximum rainfall intensity for your region on the United States Weather Bureau website. This information can be beneficial in determining your gutter size. A higher rainfall intensity will mean that rainwater will flow much faster, and a larger gutter will be necessary to handle this. Once you have your roof drainage area, your roof pitch factor, and the maximum rainfall intensity for your region, you can calculate the adjusted square footage of your gutter system by multiplying each of these values. This will give you the gutter size required to drain your roof correctly.

Adjusted Square Footage

Whether repairing an existing gutter system or installing new gutters, the proper size is essential to ensure that the drainage system does its job and carries water away from the home. If your gutters are too small, they may clog more frequently, overflow during heavy rainfalls, or not catch rainwater. To find the correct gutter size, start by measuring the square footage of the roof surface. Safely climb a ladder and use a tape measure to get a reading at one corner of the gutter run. Repeat this process at each corner of the gutter run, then add up the total measurement to get the overall length of the gutter run. You can then multiply this number by the roof pitch factor and rainfall intensity to determine what size gutter you need. Most gutter manufacturers provide comparison tables to help homeowners make this calculation. These can be found on their websites.


The gutter system isn’t complete without its downspouts, which channel water from the roof to the ground. Just like the gutters, downspouts come in various sizes and materials, from aluminum to copper (which develops a beautiful natural patina over time), galvanized steel, and vinyl. To determine the recommended size, multiply the square footage of your home’s drainage area by the roof pitch factor and the maximum rainfall intensity. This will give you the adjusted square footage to be compared to the applicable chart. Gutter systems that are too small will become overloaded during heavy rains, resulting in clogging, requiring frequent cleaning, or even failing to catch rainwater run-off altogether. Installing more oversized gutters can help prevent this issue, but it is essential to remember that bigger is not always better when it comes to gutters. Oversized gutters can look unsightly and increase the cost of your gutter replacement project.