Best Heat Cable for Gutters: How Many Feet You Need and What It Costs to Run

A 40 ft run of gutter and downspout takes 130 to 170 ft of heat cable, not 40. Sizing, cost per day, shingle vs metal roofs, GFCI safety, five picks.

11/5/20263 min read

Curb Calc cover: Best Heat Cable for Gutters, a table of cable feet by eave length and overhang, with a photo of icicles on a snowy gutterCurb Calc cover: Best Heat Cable for Gutters, a table of cable feet by eave length and overhang, with a photo of icicles on a snowy gutter

Last winter your gutter froze into a solid bar of ice, and a brown stain spread across the ceiling under the eave. Heat cable keeps a drain path open if it's up before the next storm, but a 40-foot run of gutter and downspout takes 130 to 170 feet of cable, not 40, by Frost King's sheet.

Quick pick: Frost King RC160 for a 30 ft shingle eave, 12-inch overhang; a 24-inch overhang needs the RC200. Metal or flat roof: Radiant Solutions HeatTapePro, but one kit is 37 ft, so size it with Radiant's calculator.

Free calculator: melt water pooling at the downspout? Size a gravel splash strip in our free gravel calculator.

Snow-covered roof edge with a gutter full of ice and icicles hanging below, blue sky behind
Snow-covered roof edge with a gutter full of ice and icicles hanging below, blue sky behind

Photo: Linus Belanger on Unsplash

How many feet of heat cable you need

The rule: Frost King's instruction sheet multiplies each eave by its overhang: 4.0 for 12 inches, 5.3 for 24, 6.8 for 36. Then add each downspout once (twice if mid-run).

Measure: each eave, overhang and downspout; see roofline math.

15 ft eave, 12-in overhang: 60 ft. With a 24-in overhang: 80 ft.

30 ft eave plus a 10 ft downspout: 130 ft at 12 inches (the 160 ft kit); 169 ft at 24 inches (the 200 ft kit).

The pattern: 15-inch zigzags up from the overhang, a clip at each bend, the tail down the gutter and spout. Keep drip loops at least 2 inches above the gutter bottom.

Row of icicles along the eave of a dark shingle-sided house with white-trimmed windows
Row of icicles along the eave of a dark shingle-sided house with white-trimmed windows

Photo: Brooke Balentine on Unsplash

What it costs to run

Watts: Frost King's sheet lists 300 W for 60 ft and 800 W for 160 ft, 5 W per foot. (Its blog says 7 W; we use the sheet.)

Rate: U.S. homes paid 18.16 cents per kWh in August 2026 (EIA).

On around the clock: 60 ft costs about $1.31 a day; 160 ft about $3.49, or about $105 for 30 days.

Cut the hours: Frost King says plug in before the snow starts and unplug once it's above freezing.

Icicles hanging from a snow-packed gutter below white vinyl siding
Icicles hanging from a snow-packed gutter below white vinyl siding

Photo: Linus Belanger on Unsplash

Shingles, metal or flat roof

Shingles: Frost King says its kits are for shingle roofs, not metal.

Metal, flat, wood or rubber: HeatTapePro's listing says it's certified for those and won't short if overlapped.

HEATIT: don't let it cross itself; uncoil it fully before plugging in.

Long icicle hanging from a white gutter corner above an entry light on a brick and gray-paneled house
Long icicle hanging from a white gutter corner above an entry light on a brick and gray-paneled house

Photo: Zahraa Hassan on Unsplash

Safety: GFCI, no overlap, dry day

GFCI outlet: Frost King says to use a GFI outlet; if none is close, have an electrician add one. Install on a dry day.

Roof type: Frost King's sheet says never on a flat roof or combustible materials. The cable can't be cut to fit; cutting it voids the warranty.

Thick snow on a roof with a row of icicles along the eave, bare tree branches beside
Thick snow on a roof with a row of icicles along the eave, bare tree branches beside

Photo: Wenhao Ruan on Unsplash

When heat cable is the wrong fix

The cause: NDSU Extension says heat lost into the attic is the major cause of ice dams, and northern attics need roughly 15 inches of insulation.

Its verdict: "Trying to remedy the ice dam problem with electric cables on the roof deck also is wasting energy."

Not a fit: a whole roof that dams every winter. Fix insulation and venting first; save cable for a valley or downspout that keeps freezing.

Also see: roof rakes.

Icicles hanging from a dark gutter beside a red brick wall
Icicles hanging from a dark gutter beside a red brick wall

Photo: Danielle-Claude Bélanger on Unsplash

Heat cables for gutters (#ad)

As an Amazon Associate, Curb Calc earns from qualifying purchases.

Frost King RC60 Roof Cable: 60 ft, 300 W, for shingle roofs, clips included. See it on Amazon

Frost King RC160 Electric Roof Cable Kit: 160 ft, 800 W, per the listing. See it on Amazon

HEATIT HIRD 60 ft Roof & Gutter De-Icing Cable: 5 W per foot, ETL and CSA cable, UL plug, clips included, per the listing. See it on Amazon

Frost King RC200 Electric Roof Cable Kit: 200 ft, 120V x 1000W. See it on Amazon

Radiant Solutions HeatTapePro, 37 ft: self-regulating, UL listed, for metal and flat roofs, per the listing. Clips sold separately. See it on Amazon

Heat cable FAQ

Do gutter heating cables work?

They keep a drain path open if they're on before snow. NDSU says insulation and venting fix the cause.

How long should heat tape be for a 40 ft gutter?

With a 10 ft downspout: 170 ft at a 12-inch overhang (the 200 ft kit), about 222 ft at 24 inches (Frost King's sheet).

Can I leave roof heat cable on all winter?

Left on 24/7, 160 ft costs about $3.49 a day. Unplug once it's above freezing.

Watch Curb Calc on YouTube: youtube.com/@curbcalc

Sources: Frost King FAQ; Frost King install guide; Frost King instruction sheet; NDSU Extension, 2013; EIA Table 5.6.A.