Gutter Calculator

Gutter material takeoff turns your roof’s edge length into a shopping list: how many gutter sections, connectors, downspouts, end caps, and hangers to buy. It answers “what goes in the cart,” not “what size gutter do I need.” For sizing by roof area and rainfall, use the Gutter Size calculator instead.

How the counts work:

Gutter sections = Roof edge length ÷ section length, rounded up. Sections are 10 ft in the US (3 m metric) and join end to end along each run.

Connectors = sections − 1. Every joint between two sections needs a slip connector or a sealed seam.

Downspouts = Roof edge length ÷ downspout spacing, rounded up. One downspout every 20 to 40 ft is typical; closer spacing drains faster and is worth it in heavy-rain regions.

Hangers = Roof edge length ÷ hanger spacing. Hidden hangers go about every 24 to 30 inches, closer in snow country since ice loads the gutter.

End caps = 2 for a simple straight run. A roof with several disconnected runs needs 2 caps per run, so bump this up if your roofline is broken into separate sections.

A note on corners: most houses have inside or outside corners where two runs meet. Each corner takes a mitered corner piece, and a corner is not a spot for an end cap. Count corners from the roofline and add that many corner pieces.

Downspout placement. Put downspouts at the low end of each slope and at corners, aimed away from the house. A downspout that dumps next to the wall just moves the water into your basement, so use extensions or splash blocks to carry runoff at least 4 to 6 feet out.

Worked example: A house with 120 ft of roof edge and a downspout every 30 ft:

• Sections: 120 ÷ 10 = 12 ten-foot sections
• Connectors: 12 − 1 = 11
• Downspouts: 120 ÷ 30 = 4
• End caps: 2
• Hangers: 120 ÷ 2.5 = 48 (one about every 30 inches)