Gutter Calculator
Gutter sections & hangers for your roofline
Replacing gutters? Enter the total roofline length to estimate the gutter sections and hangers you need.
Sizing gutters
Gutters come in 10-foot sections (seamless gutters are cut to length on site). Plan a hanger about every 2 feet, and a downspout for roughly every 30–40 feet of gutter.
5-inch vs. 6-inch
Standard 5-inch K-style gutter handles most homes; step up to 6-inch for large or steep roofs that shed water fast, or in regions with heavy downpours. Bigger gutters paired with 3×4 downspouts clog and overflow less than the common 2×3 size.
Slope and downspouts
Gutters need a slight slope — about ¼ inch of fall per 10 feet — toward the downspouts so water actually drains. Position downspouts at the ends of runs and away from walkways, and extend them at least 3–4 feet from the foundation so roof water doesn't pool against the house.
Gutter Calculator: frequently asked questions
How far apart should gutter hangers be?
About every 2 feet, and closer (every 18 inches) in regions with heavy snow.
How many downspouts do I need?
Roughly one per 30–40 feet of gutter, with more for steep or large roofs.
What size gutters do I need?
Most homes are fine with 5-inch K-style gutters and 2×3 downspouts. Choose 6-inch gutters with 3×4 downspouts for large, steep roofs or heavy-rain climates to prevent overflow and clogging.