Gutter Slope Calculator Open Calculator
Outlet layout

Gutter Spread Calculator

Spread downspouts evenly along a long gutter so no section drains too far — and read the spacing and fall for each segment.

Downspout spread planner
Live
Outlet layout along the gutter
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Gutter Outlet / downspout
Spread plan
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Outlets
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Spacing between outlets
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Run per outlet (high→low)
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Fall per segment
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The gutter spread calculator answers a practical layout question: across one long gutter, where should the downspouts go? Set the total length and either cap how much gutter each outlet may serve or fix the number of outlets. The tool divides the run into equal segments, reports the spacing between outlets, the run each outlet drains, and the fall that segment needs, then sketches the layout so you can see it before you set out.

Planning the spread

Even outlets, short runs

Interactive — spread outlets along the run
total gutter length outlets spaced evenly each section falls to its outlet

Want to size the outlets to the actual storm instead of a rule of thumb? Pair this with the gutter flow calculator. To check the fall on any single segment, use the gutter fall calculator.

Frequently asked

Questions answered

What is gutter spread?
Gutter spread is how the downspouts (outlets) are distributed along a gutter run — how many there are and how far apart they sit. Good spread keeps every section of gutter short enough to drain quickly and stops water travelling too far before it reaches an outlet.
How far apart should gutter downspouts be?
A common rule of thumb keeps each outlet serving no more than about 35–40 feet (roughly 10–12 m) of gutter. On long walls that means spreading two or more outlets evenly, or crowning the gutter in the middle and draining both ways.
How do I space downspouts evenly?
Divide the total length by the number of outlets to get the spacing, and place an outlet near the low end of each equal segment. The calculator does this for you and also gives the fall each segment needs.
How many downspouts for a long gutter?
Cap the spread per outlet and round up: a 60 ft run capped at 35 ft per outlet needs ceil(60 ÷ 35) = 2 outlets, about 30 ft apart. Enter your length above and try different caps to compare layouts.
Does each spread segment need its own fall?
Yes. Each section between high point and outlet must fall toward that outlet. The tool reports the fall per segment so you can mark each high point and slope down to the nearest downspout.

Need the full gutter slope toolkit?

Switch between drop, slope check, max run and downspout planning on the main calculator — with the same live diagram.

Open the main calculator