Gutter and downspout calculator
Estimate gutter sections, hangers, downspouts, elbows, and end caps from eave length and spacing.
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Tool guide
Gutter and downspout calculator: how it works
Practical information to understand the result and use this tool correctly.
About Gutter and downspout calculator
Enter the house as a closed rectangle, front and back only, one fascia, or a known eave length. Order length is that run times 1 plus the waste percent. Sections are the order length divided by the stock length you buy (often 10 ft or 3 m), rounded up.
A closed loop uses four outside corners and no end caps, because the gutter meets itself. Open runs use two end caps per run and no corners unless you add them. Downspouts are the eave length divided by your spacing (about 30 ft / 9–10 m in moderate rain), rounded up, with at least one.
Hangers follow the spacing you set: about 24 in / 0.6 m on 5-inch K-style, closer in snow country. Elbows default to two per downspout for a typical offset. This is a material count, not a hydraulic sizing for 5-inch versus 6-inch gutter or a local code check.
Nothing is uploaded. Zero, negative, and oversized lengths are rejected so a typo does not look like a real order.
How to use it
- 1Choose meters or feet, then a closed loop, open sides, or a known length.
- 2Pick a stock-length preset or enter section length, hanger spacing, and downspout spacing.
- 3Set elbows per downspout, extra corners, waste, and optional prices.
- 4Review sections, hangers, downspouts, and elbows, then copy the order.
Frequently asked questions
- How is the gutter count calculated?
- Eave length comes from the layout (2 × (length + width) when closed). Order length is eave × (1 + waste). Sections are that length divided by stock length, rounded up. Hangers and downspouts use your spacing, also rounded up.
- Does this replace the roof or fence calculator?
- No. The roof tool counts shingle squares and bundles. The fence tool counts posts, rails, and pickets. This one only counts gutter sections, hangers, and downspouts along the eaves.
- How far apart should downspouts be?
- A common planning figure is one downspout about every 30 ft (9–10 m) of gutter, closer on steep roofs or heavy-rain sites. The heavy-rain preset uses 20 ft / 6 m. Confirm outlet size with the gutter maker.
- Does the calculation leave the browser?
- No. Lengths, prices, and the order summary stay on your device.