Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Estimated total cost
$1,600
Downspouts needed
4
Gutter material
$1,260
Downspout cost
$340
Cost per linear foot
$11.43
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter total gutter run (ft).
- 2Enter roof area draining (sq ft).
- 3Enter gutter price ($/ft).
- 4Enter cost per downspout ($).
- 5Read your estimated total cost on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
Rule of thumb: one downspout per 30 to 40 feet of gutter, and one per 600 to 800 square feet of roof drainage. Undersized downspouts overflow long before the gutter does.
Worked example
Using the values the calculator loads with:
Inputs
- Total gutter run: 140 ft
- Roof area draining: 1600 sq ft
- Gutter price: 9 $/ft
- Cost per downspout: 85 $
Results
- Estimated total cost: $1,600.00
- Downspouts needed: 4
- Gutter material: $1,260.00
- Downspout cost: $340.00
- Cost per linear foot: $11.43
What each field means
Inputs
- Total gutter run (ft)
- The total gutter run used in the calculation, measured in ft. Starts at 140 ft so you have a working example on load.
- Roof area draining (sq ft)
- The roof area draining used in the calculation, measured in sq ft. Starts at 1600 sq ft so you have a working example on load.
- Gutter price ($/ft)
- The gutter price used in the calculation, measured in $/ft. Starts at 9 $/ft so you have a working example on load.
- Cost per downspout ($)
- The cost per downspout used in the calculation, measured in $. Starts at 85 $ so you have a working example on load.
Results
- Estimated total cost
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Downspouts needed
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Gutter material
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Downspout cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Cost per linear foot
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the gutter calculator work?
Rule of thumb: one downspout per 30 to 40 feet of gutter, and one per 600 to 800 square feet of roof drainage. Undersized downspouts overflow long before the gutter does. The underlying maths is: Downspouts = max(Run ÷ 35, Roof area ÷ 700), rounded up.
What do I need to enter?
4 values: total gutter run, roof area draining, gutter price, and cost per downspout. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the estimated total cost result mean?
It is returned as a money amount in US dollars and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Estimates assume standard, average conditions — local rules, pricing, and materials vary.
Who is this tool for?
It's built for anyone doing everyday planning maths — a quick estimate that would otherwise need four browser tabs and a calculator app.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Gutter Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/gutter
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/gutter" target="_blank" rel="noopener">Gutter Calculator — RevenueLab</a> (2026).</p>
Source: [Gutter Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/gutter) (2026).