Disclaimer

Last updated: September 2026. Please read this page carefully before using our calculators.

Educational information only

All content on GutterMath — calculators, articles, tables, and examples — is published for general educational purposes. It is not gutter advice and is not a substitute for a qualified professional. We are not licensed gutter contractors, and no client or advisory relationship is created by your use of this Site.

Gutter sizing depends on local rainfall intensity, roof pitch, and catchment geometry; two-story valleys and steep pitches concentrate flow beyond simple area math. Ladder work at roof edges is a leading cause of home fall injuries — two ladders, a stabilizer, and a spotter are the minimum.

Verify local rainfall intensity (NOAA Atlas 14) for sizing-critical projects, and confirm fascia condition before hanging new gutters — rotten fascia is discovered, not estimated.

Accuracy of calculations

We implement well-known, publicly documented formulas (see the methodology section on each calculator page and SMACNA and NOAA rainfall-atlas methods as applicable). Even correctly implemented formulas produce estimates that depend on your inputs and assumptions. Real-world outcomes vary. Do not rely on a single web tool for a consequential decision.

Advertising disclosure

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Errors and corrections

If you spot an error, please email hello@guttermath.app with the inputs you used. Verified corrections are published promptly.