Gutter & Downspout Cost Calculator

Gutter runs along the eaves, so it is the length of the roof edges that shed water. On a simple gable roof that is the two long sides — 2 × the building length; on a hip roof it is all four sides, 2 × (length + width). A 40 × 30 ft house with gutters on the two long sides needs 80 ft of gutter; all four sides, 140 ft. The calculator works it out from your building size or a length you enter.

A common rule is one downspout for every 30–40 ft of gutter, so gutters drain before they overflow in a downpour — and at least one at each end of a run. That 80 ft of gutter wants two or three downspouts. Bigger roofs and heavy-rain areas want them closer; the calculator spaces them from the run and you can tighten the spacing.

Installed, aluminum K-style gutter runs roughly $6–$12 per foot, seamless a little more, and copper far more; downspouts are similar per foot. Materials alone are about $2–$5 per foot for aluminum. Enter your price per foot for the gutter and a price per downspout, plus a labor rate, and the calculator totals the material-plus-labor cost.

Sectional gutter comes in 10 ft lengths (also 5 ft) that you join, so the calculator divides your run by the section length and rounds up. Seamless gutter is rolled to length on site from a machine, so it is priced by the foot with no joints. Either way, order a little extra for corners, end caps and mistakes.

Yes — the bigger the roof area draining to a run, and the harder it rains, the more the gutter and downspouts have to carry. Most homes use 5 in K-style gutter with 2 × 3 in or 3 × 4 in downspouts; large or steep roofs step up to 6 in gutter and 3 × 4 in downspouts. This tool sizes the length and downspout count; step up the profile for a big or steep roof.