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Gutter Calculator

Estimate gutter sections and downspouts needed for a roofline.

Gutter is eavestrough in Canada.

  • Answers as you type
  • Every formula cited
  • Calculated in your browser
SettingsSettings for this calculationUS
Market
Imperial · sales tax
The total length of roofline that needs gutters.

Measure along each eave (the lower edge of a sloped roof) that will have gutters, and add them together.

Tools needed: Tape measure or measuring wheel, Ladder (for accurate roof-edge measurement)

Gutter sections needed

5 x 10 ft sections

Medium confidence

Downspout count is a general rule of thumb — heavier rainfall climates or steeper/larger roofs may need more frequent downspouts for adequate drainage.

Eave length
49 ft
Downspouts needed
2 downspouts
Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • Gutter is commonly stocked in 10 ft sections in North America and 4 m lengths in metric markets; one downspout per approximately 35 ft (10.7 m) of gutter run is a standard rule of thumb for adequate drainage

Inputs used

Total Eave Length
49 ft

Intermediate steps

Eave length
49 ft
Downspouts needed
2 downspouts
Final result5 x 10 ft sections

Confidence note: Downspout count is a general rule of thumb — heavier rainfall climates or steeper/larger roofs may need more frequent downspouts for adequate drainage.

What this calculation does not cover

  • Section count is pinned to one stock size per measurement system — 10 ft lengths in imperial, 4 m lengths in metric — so a run built from 2 m half lengths, from longer aluminium stock, or from seamless gutter rolled continuously on site will not match the number shown.
  • Your total eave figure is divided by that stock length and rounded up exactly once, which treats the whole roofline as one uninterrupted run; where the guttering stops and restarts at a hip, a gable or a porch, every break leaves an offcut, and no waste allowance is added to cover them.
  • Eave length is the only measurement taken, so the answer counts lengths rather than sizing them — the profile, depth and cross-section of the gutter, and the diameter of the downspouts, are all still yours to choose.
  • Running outlets, unions and stop-ends each take up part of the finished run, but the downspout figure is worked out on its own and is never deducted from the length being divided into sections.
  • That downspout figure comes from the total eave length and is floored at one, so a roofline split across several elevations can be answered with fewer outlets than it has separate gutters — each independent run needs one of its own.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

49 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Part of bigger jobs

This trade is one line of several job takeoffs. Run the whole job and every other trade comes back with it, off the same measurements.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-05 · in the site-wide review of 2026-09-06 · v1.0.1

Regulatory standards & verification citations1
  1. Gutter is commonly stocked in 10 ft sections in North America and 4 m lengths in metric markets; one downspout per approximately 35 ft (10.7 m) of gutter run is a standard rule of thumb for adequate drainage
Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Tools and safety for this job

To fit gutters and downpipes. Generic types, no brands, no prices.

Protection this work requires

  • Boards, blocks and bagged material cause most lasting back injuries on small sites: two people or a lifter for full sheets, and never a bag on one shoulder up a ladder.
  • Most fatal falls on small jobs are from under three metres: use a tower or a ladder tied at the top, and never work off the top two rungs.
Show the 5 tools this job needs

Essential

  • Cordless drill/driver

  • Hand saw

  • String line and pins

  • Tape measure

Recommended

  • Spirit level

Also needed as materials: drill and driver bits.

what each roofing tool is for, and the spec that decides which to buy where one does.

Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

Called something else where you work? Gutter / eavestrough · Downpipe and rainwater discharge — the term in each market, how close the equivalence really is, and the standard that governs it.

Still deciding? Gutter Guards vs Cleaning — the factors that actually differ, with no invented prices.

Already gone wrong? My gutter overflows when it rains hard · There is a water stain on my ceiling · There is a white powdery deposit on my brickwork

The data behind it: Production rates by operation

How to calculate gutter in 2 steps

  1. Total Eave LengthThe total length of roofline that needs gutters.
  2. Gutter sections neededThe tool computes the gutter sections needed from those figures and shows the formula, its sources, and a confidence rating alongside it.

Gutter sections needed by total eave length

Page defaults, not your figures above.

Total Eave LengthGutter sections needed (x 10 ft sections)
20 ft2
40 ft4
60 ft6
80 ft8

Frequently asked questions

What is actually being sized here — the length, or the water?
The water. A gutter is a channel with a flow rate to meet, and the length you are ordering is only the visible half of the answer: what governs the size of the section is how much rain lands on the roof behind it and how fast the outlets can take that away. Catchment is the roof's PLAN area, not its sloped area, because rain falls vertically — a steeply pitched roof sheds no more water than a shallow one of the same footprint, though it delivers it faster. That is also why a long run with one outlet at the end is a different problem from the same run with an outlet at each end: halving the distance water must travel roughly doubles what the same section will carry. Undersize it and the gutter does not merely overflow in a storm, it overflows at the back edge, which is the side with the fascia on it.
Does this include corners and end caps?
No — this estimates straight gutter sections only. Corner pieces, end caps, and hangers are additional hardware calculated per corner and per section, not by length.
Why does downspout placement matter?
Too few downspouts for a given gutter run can cause overflow during heavy rain, leading to water damage at the foundation — spreading them out per the rule of thumb here helps avoid that.
Should downspouts go at the lowest point of a run?
Gutters are sloped slightly toward each downspout, so downspouts are placed at the low points of each sloped section — your specific roofline's slope may affect exact placement beyond what this length-based estimate covers.
Why count sections, when a lot of gutter is seamless?
Seamless aluminium gutter, the usual kind on North American houses, is roll-formed on site to each run's exact length, so there are no sections to count: the order is the run's length and its fittings. This count serves sectional gutter, which is joined at every length by a union or connector: the PVC gutter sold at British merchants in 4 m (13 ft) and 2 m (6 ft 7 in) lengths, and the vinyl and steel sections sold in North America in 10 ft (3.05 m) lengths.
Which gutter profile is usual on each side of the Atlantic?
On a British house the common domestic gutter is PVC half-round, 112 mm (4 1/2 in) across, with square, deep-flow and ogee profiles for bigger roofs and older houses. In North America it is K-style, a flat back with an ogee front, in 5 in (127 mm) or 6 in (152 mm), with half-round kept for period houses. The profile does not change the length ordered here, but it decides which corners, unions, outlets and brackets fit, because they are made for one profile and one maker's range.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.