Choosing the right gutter size is more important than many homeowners realize. Undersized gutters can overflow in heavy rain, leading to foundation issues, erosion, and water damage. Oversized gutters may cost more than you really need. A few key measurements and concepts will help you pick the right system for your home and your budget.
How Are Gutters Measured?
When people talk about “5‑inch” or “6‑inch” gutters, they’re referring to the width across the top opening of the gutter, from the back edge that mounts to the fascia to the front lip. Residential K‑style gutters are most commonly:
- 5‑inch wide
- 6‑inch wide
The depth and profile can vary by manufacturer, but that top opening controls how much water the gutter can handle at once. Larger gutters pair with larger downspouts, which is critical to keep water moving: for example, 5‑inch systems often use 2x3 or 3x4 downspouts, while 6‑inch systems may use 3x4 or even 4x5 downspouts so the downpipe doesn’t become a bottleneck.
What Size Gutters Do Most Homes Need?
For many standard homes with relatively simple rooflines and average rainfall, 5‑inch K‑style gutters are the typical choice. They are cost‑effective and handle normal roof drainage well when paired with correctly sized downspouts and enough outlets.
However, 6‑inch gutters are becoming more popular because they can move significantly more water—often up to 40–50% more capacity than a 5‑inch system when combined with larger downspouts. They are often recommended when:
- The roof is large or has long runs.
- The roof is steep, which sends water into the gutters faster.
- There are multiple valleys that concentrate water into certain sections.
- You’ve had overflow problems with existing 5‑inch gutters.
- You plan to add gutter guards, which can slightly change flow dynamics.
How to Think About Gutter Sizing (Beyond “5 vs 6”)
Professionals look at the roof drainage area and expected rainfall intensity to size gutters and downspouts. The bigger the roof area feeding a gutter run—and the heavier your local storms—the more capacity you need. A properly sized system balances three things:
- Gutter width (5" vs 6" for most homes).
- Downspout size (2x3, 3x4, or larger).
- Number and placement of downspouts along the run.
You don’t have to do full engineering calculations to make a good choice, but it helps to:
- Note which sections of your roof collect the most water (big valleys, long eaves).
- Check for signs that current gutters are undersized: frequent overflows, water staining, or erosion below downspouts.
- Consider moving up to 6‑inch gutters in problem areas or on large/steep roof planes while using standard sizes elsewhere.
Actionable Steps to Choose Your Gutter Size
To make a confident decision:
- Walk your home during a heavy rain and look for overflow points.
- Measure approximate roof sections feeding each gutter run (length x approximate slope width). Larger sections may need 6‑inch gutters and/or bigger downspouts.
- Think ahead about gutter guards—if you plan to add them, factor that into size and downspout choices.
- Ask for local guidance from a supplier who understands Midwest rainfall and typical roof designs.
Where to Buy Gutters and Supplies
If you are wondering where to buy gutters and all the accessories you need, A to Z Supply is your local source. A to Z Supply offers:
- 5‑inch and 6‑inch gutter systems and components.
- Matching downspouts, elbows, hangers, and outlets sized correctly for your system.
- Gutter guards and accessories to improve performance and reduce maintenance.
Don't forget—A to Z Supply goes well beyond gutters! Local contractors and homeowners rely on us for roofing, siding, decking, windows, doors, trusses, fencing, sheet metal, garage doors, and more!
Planning a new gutter installation or upgrading an existing system? Contact A to Z Supply for help selecting the right gutter size, layout, and materials so your home stays better protected in every storm.