Free Tool
Free gutter and downspout calculator
Enter your eave length and downspouts to get the gutter linear feet, downspout footage, hangers, and outlets. Free, no signup.
Add up every run of gutter
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Every run, drop, and hanger
A gutter job is more than the trough. It is the gutter along the eaves, the downspouts that carry the water down, and the pieces that hold it all together. Enter the eave length and the number of downspouts and the calculator lays out the parts.
Gutter footage is the total length of your eaves, so add up every run. Downspout footage is the number of drops times how far they run down, which is why a two-story wall needs a longer drop than a single story.
Hangers hold the gutter to the fascia, spaced about every 2 feet, and closer where snow and ice load the run. Each downspout needs a drop outlet cut into the gutter and a pair of elbows to bring the pipe back to the wall and turn it out at the bottom.
Slope matters as much as the count. Pitch each run toward its downspout, about a quarter inch every 10 feet, so the water actually leaves instead of standing and overflowing.
Gutter Calculator questions
How much gutter do I need?
Add up the length of every eave run. The calculator takes that plus your downspouts and returns the gutter, downspout footage, hangers, and outlets.
How many downspouts do I need?
A common rule is one downspout per 30 to 40 feet of gutter, more on a steep or large roof. Enter your count and the calculator sizes the drops.
How far apart do gutter hangers go?
About every 2 feet, closer in snow country. The calculator estimates the hangers from your eave length.
Is this really free?
Yes. No email, no signup, and nothing you type leaves your browser.
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Disclaimer: These free tools and templates are provided for general information and estimating purposes only. All results — including quantities, material and cost estimates, load, sizing, and span figures, scores, and any guidance or warnings — are rough approximations that may not fit your specific project, site conditions, local building codes, or current prices. They are not engineering, architectural, structural, legal, financial, or other professional advice, and are not a substitute for a licensed engineer, architect, contractor, or other qualified professional. Always confirm quantities, sizing, and structural, electrical, mechanical, and code requirements with a licensed professional and your local authority having jurisdiction before purchasing materials or performing any work. Werx makes no warranty as to accuracy and accepts no liability for any decision made using these tools. Use at your own risk. See our Terms of Service.