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Gutter Calculator
Estimate linear feet of gutter, the number of downspouts, hangers, elbows, and end caps for your roof — so you buy the right materials in one trip.
Results update automatically as you type.
How gutter estimating works
Four numbers cover almost every gutter job: the linear feet of gutter (your total eave length), the number of downspouts (driven by both gutter length and roof area), the hangers that hold it up, and the fittings (end caps and elbows). Get those right and the material list falls into place.
Sizing your downspouts
Downspouts are the part most people under-buy. Use the stricter of two rules: one downspout per 30–40 feet of gutter, and one per 600–800 sq ft of roof draining into that gutter. A big roof on a short eave still needs enough downspouts to move the water.
Hangers, end caps, and elbows
- Hangers: every 24 inches (every 18 inches in snow country) — roughly one per two linear feet.
- End caps: two per separate gutter run (left and right).
- Elbows: about three per downspout to get from the gutter, over the eave, and down the wall.
5-inch vs 6-inch gutters
Five-inch K-style handles most homes. Step up to six-inch for large roof areas, steep pitches that dump water fast, or high-rainfall regions — the extra capacity prevents overflow during heavy storms.
Frequently asked questions
How many downspouts do I need?
At least one per 30–40 ft of gutter and one per 600–800 sq ft of roof. Long or steep roofs need more.
How far apart should hangers be?
Every 24 inches normally; every 18 inches in heavy-snow areas.
Do I need 5-inch or 6-inch gutters?
5-inch suits most homes; 6-inch for large or steep roofs and heavy rainfall.