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Gutter Calculator: Sections, Hangers and Downspouts

Enter the total length of gutter along the eaves, how many separate runs there are, the downspouts and the height of the eaves. You get the gutter sections, the hangers, end caps, outlets, corners, the downspout parts and how much the gutter must slope.

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Your project

A run is a length of gutter with an end cap or a corner at each end, such as the front of a house.

One for every 20 to 30 ft of gutter is the usual guide.

Results

Example job shown. Change the numbers to match yours.

Gutter sections of 10 ft
6 sections
For 60.0 ft of gutter
Connectors (joints)Each join between two sections is sealed
4 joints
HangersOne every 24 in, plus one at the end of each run
32 hangers
End capsTwo for each run
4 caps
Drop outletsOne for each downspout
3 outlets
Corners0 inside, 0 outside
0 corners

Downspouts

Downspout sections of 10 ft1 for each downspout, cut to length
3 sections
ElbowsTwo at the top to reach the wall, one at the bottom
9 elbows
Downspout strapsAbout one every 5 ft, at least 2 for each downspout
6 straps

Slope

Drop along the whole run at 1/4 in per 10 ftIf the outlet is in the middle the gutter falls both ways from the high point
1.50 in
Downspouts suggested at one per 30 ftMore for a big or steep roof, or if the gutters overflow
2 downspouts
  • This is for 5 inch K-style gutters in 10 ft sections, the usual size on a house. The gutter slopes about 1/4 inch for every 10 ft toward the downspout, and hangers go about every 24 inches (closer where there is heavy snow). A big or steep roof, or one in a rainy region, may need 6 inch gutters and more downspouts. Use parts from the same system and seal every joint. A gutter is fixed high up: use a safe ladder or hire a pro for a second story.

Before you buy: round up to whole packs, check the size printed on the label, and add a little spare. Your supplier has the final say.

How this calculator works

K-style gutters come in 10 ft sections, so the number to buy is the run divided by 10, rounded up. Each join between two sections is sealed with a connector, and the gutter hangs from a hanger about every 24 inches. Each run has an end cap at both ends, each downspout needs an outlet cut into the gutter, and a downspout is made of 10 ft sections and elbows. The gutter slopes about 1/4 inch for every 10 ft toward the downspout.

sections = run ÷ 10, rounded up hangers = run in inches ÷ spacing, rounded up, plus one for each run slope = run ÷ 10 × 1/4 in

Worked example: 60 ft of gutter in two runs takes 6 sections and 4 connectors. With a hanger every 24 inches that is 32 hangers, with 4 end caps and 3 outlets. Three downspouts 10 ft high take 3 sections, 9 elbows and 6 straps. The gutter slopes 1.50 inch over the whole run. In heavy snow country, hangers every 18 inches take 42. A single run of 30 ft with one downspout takes 3 sections and 16 hangers. A run of 100 ft in one piece takes 10 sections and 51 hangers, and a big house of 120 ft in four runs with five downspouts 20 ft high takes 12 sections, 64 hangers and 10 downspout sections.

Parts for common runs of gutter (10 ft sections, one run, hangers 24 in apart)

Sections, connectors, hangers and the slope.

Run of gutterSectionsConnectorsHangersSlope along the run
20 ft21110.50 in
30 ft32160.75 in
40 ft43211.00 in
60 ft65311.50 in
80 ft87412.00 in
120 ft1211613.00 in
160 ft1615814.00 in

Tips before you buy

  • Measure along the fascia where the gutter will hang, and add the corners and the end caps.
  • Set the high end first, then snap a chalk line down to the low end for the slope: about 1/4 inch every 10 ft.
  • Put a hanger within a foot of each joint and corner, and space the rest about 24 inches apart (18 where there is snow).
  • Seal every joint with gutter sealant, and put the sections together so that the water runs over the joint, not into it.
  • Clean the gutters in the fall and the spring, or fit guards.

Tools & materials for this project

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K-style gutter 10 ftGutter hangersGutter sealantDownspout 10 ftGutter guards

Frequently asked questions

How much gutter do I need?

The length of the eaves where the gutter goes, in 10 ft sections: 60 ft takes 6 sections, with 4 connectors.

How many gutter hangers do I need?

One about every 24 inches, plus one for each end: 32 for 60 ft. Where there is heavy snow, space them 18 inches apart: 42.

What slope should a gutter have?

About 1/4 inch for every 10 ft toward the downspout: 1.50 inch over 60 ft.

How many downspouts do I need?

One for every 20 to 30 ft of gutter. A run of 60 ft needs at least 2. Use more on a large or steep roof.

What size gutter do I need?

Five inch K-style gutters suit most homes. A large or steep roof, or heavy rain, may need 6 inch gutters.

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Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.