Gutter & Downspout Calculator
Enter the length of gutter on a home and get the downspout count, the number of hangers and an installed price. Built for gutter contractors writing estimates, and for homeowners who want to know what a new system involves.
Free, no sign-up. Runs in your browser; nothing you type is stored unless you choose to email yourself the results.
Loading calculator…
Email me these results. We'll send your numbers, plus how to turn this calculator into a lead magnet on your own website.
Three steps, about a minute
Step 1
Measure every eave that will get gutters and enter the sum as Total gutter length in feet.
Step 2
Set Downspout spacing and Hanger spacing to match how you install on this particular house.
Step 3
Add your Installed price per foot to see Downspouts, Hangers and the Estimated installed price.
How the gutter downspout calculator works
Downspouts are the total gutter length divided by your downspout spacing, rounded up, never fewer than one. Hangers are the length divided by hanger spacing, also rounded up. The estimated installed price is length times your installed price per foot. The preset job runs 160 feet with a downspout every 35 feet and a hanger every 2 feet: 5 downspouts, 80 hangers and $1,920 at $12 a foot. One downspout per 30-40 feet is a common rule of thumb, not a sizing method. The tool treats the gutter as one run, so a short separate run over a porch still needs its own outlet. On large or steep roofs, size gutters and downspouts from roof area and local rainfall intensity. The price line is length only, so build downspouts and corners into your per-foot rate.
| Total gutter length | 160 ft |
|---|---|
| Downspout spacing | 35 ft |
| Hanger spacing | 2 ft |
| Installed price per foot | $12 |
| Downspouts | 5 |
|---|---|
| Hangers | 80 |
| Estimated installed price | $1,920 |
A common guideline is one downspout per 30–40 feet of gutter.
Using the numbers like a pro: tips for gutter contractors
Count downspouts per run, not just per total foot. Every separate section of gutter needs at least one outlet, and a missed downspout is an easy way to earn an overflow callback.
List gutter guards, downspout extensions and old gutter removal as separate line items. Customers see what they are paying for, and you can upsell without reworking the base price.
Tighten hanger spacing on homes in heavy snow areas or below big roof valleys. Extra hangers cost little, while a sagging or torn-off gutter costs you a warranty visit.
Put a calculator like this on your own website
Gutter leads usually start with a problem the homeowner can see: a leak at the corner, water spilling over in a storm, a run pulling away from the fascia. A calculator on your site that turns feet of gutter into a ballpark price catches them while the problem is fresh. Ask for an address and phone number to send the estimate, then confirm it on a site visit.
Get a free audit of your marketing
Website, Google Business Profile and a Google Maps rank scan across your area. Plain English, no obligation.
Gutter & Downspout Calculator questions
How many downspouts do I need for my gutters?
A common rule of thumb is one downspout for every 30-40 feet of gutter, with at least one on every separate run. Large roof areas, steep pitches, regions with heavy rainfall and long runs that drain to one outlet may need more or larger downspouts. A gutter contractor can size them from the roof area that drains into each section.
How far apart should gutter hangers be?
Many installers place hidden hangers about every 2 feet, and closer in places with heavy snow or ice. Follow the gutter and hanger manufacturer's instructions, since the right spacing depends on gutter size, material and hanger type. Hangers also need solid fastening, so rotted fascia boards should be repaired before new gutters go up.
How do contractors price gutter installation?
Most price by the linear foot, with the per-foot rate covering the gutter, hangers and labor. Downspouts, corners, end caps, guards, removal of old gutters and fascia repair may be included or listed separately. Material, gutter size and one-piece versus sectional runs all change the rate. An itemized quote makes it easier to compare contractors fairly.
Keep going: related tools
Roof Squares Calculator
Turn a house footprint and roof pitch into surface area, roofing squares, shingle bundles and a job value at your own price per square.
Use it freeConcrete Calculator
Find the cubic yards, cubic feet and bag count for a slab, patio, pad or walkway, with extra for spillage.
Use it freeRoof Runoff Calculator
See how many gallons one storm and a full year of rain send off a roof and down toward one side of the foundation.
Use it freeSiding Squares Calculator
Work out net wall area and how many squares of siding to order from the house perimeter, wall height, gables and openings.
Use it freeGarage Door Spring Life Calculator
See how many years a garage door spring should last based on daily use and its cycle rating.
Use it freeLead Value Calculator
Find out what extra leads from marketing are worth in booked jobs and revenue, per month and per year.
Use it free