Standard Gutter Sizes

One of the best things you can do to protect your home from the damaging effects of stormwater and snowmelt is to install a complete rain gutter system that transports water off your roofline and away from the foundation. When stormwater is not drained away from your home properly, it can lead to cracks in the foundation, settling and cracking, water damage to your windows, doors and siding, soil erosion, oversaturation of flower beds and lawns, lifting underneath your driveway, and other issues that cost a good deal of money to repair.

When looking for new gutters, it’s important to make sure you choose the correct gutter size for your home and geographical location. If you pick a size that’s too small, water will overflow the gutter trough. If you choose a size too large, you’ll waste some money as well as potentially risk letting water stand in the gutter instead of draining toward the downspouts.

Modernize created this guide to standard gutter sizes to help homeowners learn what type of gutters their homes need before speaking with licensed gutter installers. We’ve covered the most common sizes, how to determine what size is appropriate for your home and rainfall density, and more.

Standard Gutter Sizes

In most climates, gutters are installed in one of two standard size widths: 5-inch or 6-inch. For half-round gutters, 6-inch gutters are the standard and more than capable of handling the harshest weather conditions. However, in drier areas, 5″ half round gutters may be suitable.

For k-style gutters, 5-inches wide is the most common size. This is because the deeper gutter trough on this style can accommodate heavy stormwater and snowmelt conditions, especially when paired with gutter guards. However, in areas with heavier than normal rainfall, 6″ k-style gutters may be a more suitable choice.

Many factors can affect how a gutter system performs, though. In some instances homeowners may want to install custom oversized gutters to ensure they properly move water off your roofline without overflowing the gutter trough. Factors that determine whether you need larger than standard size gutters include the pitch of steepness of your roof, overall size of the roofline, roof design, and maximum rainfall density in your region.

Although larger sized gutters will cost a bit more, they may be better equipped to meet the needs of your home. To get a better feel for how much gutters cost to install, we encourage you to use our free Gutter Installation Cost Calculator tool.

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Gutter Thickness

In addition to width, another important consideration when thinking about gutter sizing is the thickness of the material, or gauge. Generally speaking, thicker gutters will hold up better over time in harsh weather than thinner gutters. The best gutter gauge for your home will be based on the gutter material as well as rainfall density in your area.

Here are some common gutter materials and thickness ranges based on the type of gutter material.

Aluminum

Aluminum is by far the most common material used for gutters. Its thickness is measured in thousands of an inch. You will see aluminum gutters ranging in gauge from .019 to .032 inches. A lower number translates to a thinner gutter. The industry standard is a 0.27 gauge aluminum gutter, which is typically sufficient to withstand mild to moderate weather conditions and rainfall. However, you might need a thicker 0.32 gauge gutter if you live in an area prone to harsh weather, such as hurricanes or heavy snowfall.

Copper

Copper gutters are less common but are chosen by homeowners because they hold up well over time. 20-gauge copper gutters are the most common, but you can purchase copper gutters in 16- and 24-gauge as well. With copper, a higher number actually translates to a thinner gutter. With that being said, homes in areas with heavier than usual rainfall or snowfall may require a 16-gauge copper gutter system.

Steel

Steel gutters are sturdy and can range between 24- and 30-gauge in thickness. 26-gauge steel gutters are the most common installation in the U.S. Going thicker with a 24-gauge will better protect your home from rain and snow buildup, while choosing a 30-gauge steel gutter is a better choice for drier areas. Note that your gutter professional may recommend 26- to 28-gauge downspouts.

Vinyl

Vinyl gutters are made from standard PVC plastic. They can be a good, low-cost option in temperate climates that don’t see much wet weather or sub-freezing temperatures. If you decide to go with vinyl, make sure you talk to a professional to make sure the plastic is thick enough to support your home’s climate.

Calculating What Size Gutters Your Home Needs

A professional contractor will handle all the measurements for gutter sizing during your initial appointment. However, if you want to calculate the gutter size your home needs yourself, here’s how to do the math. Below we will help you determine what gutter size will be necessary to protect your home against typical rainwater levels in your area.

Determine your roof’s square footage

Use a tape measure to determine the length and width of each section of your roof. Multiply those numbers, then add them together to determine the overall square feet of your home’s roof.

Determine your roof’s pitch

You might need another set of hands for this one. Roofs are built with a slope, or pitch, to drain water. You can figure out the roof pitch by touching one corner of a level to your roof, leveling horizontally, measuring 12 inches out, and then measuring straight down from that 12-inch mark to the roof. This distance determines the pitch of your roof. If the down measurement is six inches, you have a 6/12 roof – there’s six inches of rise for every foot of run (incline).

Multiply roof square feet by roof pitch

Next you will multiply the total square footage of your roof by the roof’s pitch. The table below shows the multiplication factor for square footage and pitch of your roof:

Pitch Multiplyer:

Look at your total number

A number between 5,500 and 7,500 means 5-inch K-style gutters should adequately accommodate your roofline. If the number exceeds 7,500, you might consider purchasing a wider or thicker gauge gutter to handle more stormwater.

Use the calculations above as a rough guide. Your professional gutter installation contractor can walk you through the basics of selecting the right gutter for your home. Additional factors such as regional climate, rain and snowfall totals and drainage also could dictate the best gutter size for your home.

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Calculating What Size Gutter Downspouts Your Home Needs

Downspouts are also an essential aspect of a properly functioning gutter system. They transport water away from the roofline to the ground, where it can be piped away from your foundation through a French drain or left to drain naturally from the bottom of the spout, as long as it’s moving away from the foundation.

Downspouts come in a variety of shapes, including boxed, spiral and round. Boxed gutters pair well with k-style gutters, while round downspouts pair well with half-round gutters. Common downspout widths for 5-inch k-style gutters are either 2” by 3” or 3” by 4” if you need greater amounts of stormwater to flow out of the gutter trough. Half-round gutter downspouts, meanwhile, are commonly sold in 3” or 4” diameters.

According to the Sheet Metal and Air Conditioning Contractors’ National Association (SMACNA), these are the drainage capacities for common sizes of rectangular and round gutter downspouts:

Round Downspouts:

• 3″ downspouts: 706 square feet
• 4″ dowsnpouts: 1,255 square feet

Rectangular Downspouts:

• 2″ x 3″: 600 square feet
• 3″ x 4″: 1,200 square feet

Wider downspouts also can be installed to accommodate homes with larger-sized gutters.

Gutter Pitch

One reason why it’s important to hire a professional to install your new gutters is to ensure the gutters have the proper pitch when attached to your home’s fascia. Gutters don’t sit perfectly level to the ground. Instead, each section is slightly sloped to ensure all the water in the trough flows toward the downspouts.

This slight slant is imperceptible on small runs but may be more noticeable on larger sections. Installers typically add ¼” of slope per every 10 feet. So if you have a 40-foot run across one section of your home your gutters will have 1” of fall. However, installers may start the pitch from the center of longer sections, so you would have ½” of fall from the center extending to the ends of a 40-foot section.

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Choosing Custom Gutter Sizes

The vast majority of home gutters throughout the U.S. are either 5-inch k-style or 6-inch half-round gutters. However, large homes with steep-pitched roofs and homes located in regions that experience high amounts of rainfall over a short period of time may need custom gutter sizes to accommodate greater amounts of stormwater.

Choosing larger gutters – 7” or even 8” – will handle much larger volumes of water. This is important in areas with high maximum rainfall intensity, which is the greatest amount of rain that has fallen in a 5-minute period, expressed in inches of rain per hour. 

As an example, the maximum rainfall intensity in Houston for a 5-minute period is 5.93 inches per hour. In Park City, Utah, it’s 1.54 inches per hour. You can find precipitation frequency for your region using data provided by the National Oceanic and Atmospheric Administration.

It’s important to note that larger gutters will cost more. But for some homes the added expense is justified knowing stormwater is properly moving off your roof during severe weather events, and will ultimately save you money on repairs and replacements.

Finding a Local Gutter Contractor

We’ve discussed why it’s important to have a professional complete your new gutter installation project. Here’s a brief recap.

• Gutters must be sloped when installed to ensure proper drainage.
• Calculating gutter sizes for proper drainage volume involves some complicated calculations. Professionals can quickly determine gutter sizes so you don’t have to do it yourself.
• Gutter contractors have specialized roll-form machines to make seamless gutters onsite.
• Gutter installation contractors have ample experience working on ladders and at heights. They also know how to walk across roofs without breaking roof tiles or slates.

When you are ready to install new gutters on your home, Modernize can put you in touch with licensed gutter installation contractors in your area. The best practice to find the best price and professional for your project is comparing quotes from 3 to 4 local contractors.

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