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Gutter Calculator

Estimate gutter sections and downspouts needed for a roofline.

Computed in your browser — nothing you enter is uploaded. Figures are presented in United States units and terminology, and each formula’s basis is cited under regulatory standards below.

Last verified 2026-08-25 · v1.0.0

Market
Imperial · sales tax
49 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Gutter sections needed

5 x 10 ft sections

Check your inputs

Downspout count is a general rule of thumb — heavier rainfall climates or steeper/larger roofs may need more frequent downspouts for adequate drainage.

Eave length
49 ft
Downspouts needed
2 downspouts

Running these inputs gives 5 x 10 ft sections as the gutter sections needed. Expect some drift against the real job; the calculation is solid but conditions on site are not. Currently reading for United States — pick a different market above and the figures re-cast accordingly.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.

Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Regulatory standards & verification citations

  • Gutter is commonly stocked in 10 ft sections; one downspout per approximately 35 ft of gutter run is a standard rule of thumb for adequate drainage

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

Does this include corners and end caps?
No — this estimates straight gutter sections only. Corner pieces, end caps, and hangers are additional hardware calculated per corner and per section, not by length.
Why does downspout placement matter?
Too few downspouts for a given gutter run can cause overflow during heavy rain, leading to water damage at the foundation — spreading them out per the rule of thumb here helps avoid that.
Should downspouts go at the lowest point of a run?
Gutters are sloped slightly toward each downspout, so downspouts are placed at the low points of each sloped section — your specific roofline's slope may affect exact placement beyond what this length-based estimate covers.