How many downspouts do I need?

A common rule is one downspout for every 30–40 ft of gutter, and at least one per separate run. Large or steep roofs may need more.

How far apart should gutter hangers be?

24 inches is standard where snow or heavy rain is common; 36 inches is often acceptable elsewhere. Follow the gutter manufacturer's spacing.

Free tool

Gutter calculator

Gutter footage, downspouts, hangers, and fittings from eave length.

Inputs

Total eave length (ft)Eave height (ft)Separate gutter runsInside/outside cornersHanger spacing

Estimated materials

Gutter: 120 LF
Downspouts: 4 (40 LF)
Hangers: 60
End caps: 4
Corners: 2
Elbows (3 per downspout): 12

Uses one downspout per ~35 ft of gutter and at least one per run. Large or steep roofs may need more — size to roof drainage area and local rainfall. Estimate — verify before ordering.

Frequently asked

How many downspouts do I need?: A common rule is one downspout for every 30–40 ft of gutter, and at least one per separate run. Large or steep roofs may need more.
How far apart should gutter hangers be?: 24 inches is standard where snow or heavy rain is common; 36 inches is often acceptable elsewhere. Follow the gutter manufacturer's spacing.

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