Estimate linear feet of gutter and how many downspouts you need from your roofline. Quick and simple.
Estimates for planning only. Always confirm measurements and order a little extra for waste and cuts.
This calculator estimates the linear feet of gutter, the number of downspouts, and the hangers you'll need from your roofline length, so you can plan a gutter project or check a bid.
Gutter length matches your roofline. Downspouts are spaced to handle the water volume:
Gutter = total roofline lengthDownspouts = roofline ÷ spacing (about one every 30 to 40 ft)Hangers = roofline ÷ 2 (one about every 2 ft)
A good rule of thumb is one downspout for every 30 to 40 feet of gutter, with at least one per gutter run. Long runs, steep or large roofs, and heavy-rain regions (like Florida) benefit from more downspouts and larger 6-inch K-style gutters instead of standard 5-inch. Proper spacing prevents overflow that damages fascia and foundations.
One number drives everything: the total roofline you plan to gutter, in feet. Gutter footage equals that number, because gutter runs the length of the eave. Downspouts are your footage divided by the spacing you pick, 30, 35, or 40 feet, rounded to a whole drop, with a floor of two. Hangers come out as your footage divided by two, since hangers go about every 24 inches. End caps are shown as a pair per run rather than a count, because the tool has no way to know how many separate runs your roofline breaks into.
If you enter a price per linear foot, it multiplies that by the gutter footage and prints a material subtotal. Read that line carefully: it prices the gutter and nothing else. Downspouts, elbows, outlets, hangers, end caps, miters, and sealant are not in it, and neither is any labor. The tool carries no price list of its own, so leave the field blank and no dollar figure appears anywhere.
The rest is what it cannot see. It does not know your roof area, your pitch, or how hard it rains where you are, and those decide whether 5-inch K-style is enough or you should be at 6-inch with 3 by 4 downspouts. It does not count inside and outside corners, which change your miter and material list. It does not know where a downspout can physically drop, and the spacing figure is a rule of thumb, not a drainage calculation. Use it to build a shopping list and sanity-check a quote, then have someone look at the actual roof. Gutter companies who want this on their own site, with their own prices behind it, can have one built: custom calculators start from $600.
There is a hard floor of two in the math, even on a short run. Every run needs at least one outlet, and most houses have more than one run, so a single downspout is almost never right for a whole home. If your job genuinely is one short run with one drop, ignore that row and use the footage and hanger counts.
No. It is your own price per foot multiplied by your own footage, and that is the entire calculation. It leaves out downspouts, hangers, end caps, corners, and sealant, plus all labor, so a real material bill lands higher than that line. Treat it as a starting figure for the gutter itself and price the accessories separately.