The short answer
100 ft of 5 W-per-foot roof heat cable draws 500 W and costs about 9 cents an hour at the U.S. average electricity rate of 18.16¢ per kWh (August 2026). Left on all day, that's $65.38 a month or $196.13 over a 3-month winter; on a controller that runs it about 8 hours a day, $21.79 a month.
The same cable in every state
100 ft at 5 W per ft, 24 hours a day, 30 days a month for 3 months, at each state's average residential rate (August 2026).
| Alabama | $58.79 | $176.36 | 16.33¢ |
|---|---|---|---|
| Alaska | $105.88 | $317.63 | 29.41¢ |
| Arizona | $54.18 | $162.54 | 15.05¢ |
| Arkansas | $51.73 | $155.20 | 14.37¢ |
| California | $107.10 | $321.30 | 29.75¢ |
| Colorado | $61.81 | $185.44 | 17.17¢ |
| Connecticut | $88.24 | $264.71 | 24.51¢ |
| Delaware | $67.32 | $201.96 | 18.70¢ |
| District of Columbia | $93.53 | $280.58 | 25.98¢ |
| Florida | $53.96 | $161.89 | 14.99¢ |
| Georgia | $57.24 | $171.72 | 15.90¢ |
| Hawaii | $169.85 | $509.54 | 47.18¢ |
| Idaho | $48.13 | $144.40 | 13.37¢ |
| Illinois | $69.55 | $208.66 | 19.32¢ |
| Indiana | $61.27 | $183.82 | 17.02¢ |
| Iowa | $61.42 | $184.25 | 17.06¢ |
| Kansas | $55.69 | $167.08 | 15.47¢ |
| Kentucky | $49.68 | $149.04 | 13.80¢ |
| Louisiana | $46.33 | $139.00 | 12.87¢ |
| Maine | $115.60 | $346.79 | 32.11¢ |
| Maryland | $77.04 | $231.12 | 21.40¢ |
| Massachusetts | $109.73 | $329.18 | 30.48¢ |
| Michigan | $82.76 | $248.29 | 22.99¢ |
| Minnesota | $61.92 | $185.76 | 17.20¢ |
| Mississippi | $51.95 | $155.84 | 14.43¢ |
| Missouri | $57.67 | $173.02 | 16.02¢ |
| Montana | $56.05 | $168.16 | 15.57¢ |
| Nebraska | $48.74 | $146.23 | 13.54¢ |
| Nevada | $45.79 | $137.38 | 12.72¢ |
| New Hampshire | $99.50 | $298.51 | 27.64¢ |
| New Jersey | $88.60 | $265.79 | 24.61¢ |
| New Mexico | $59.44 | $178.31 | 16.51¢ |
| New York | $103.14 | $309.42 | 28.65¢ |
| North Carolina | $53.82 | $161.46 | 14.95¢ |
| North Dakota | $47.92 | $143.75 | 13.31¢ |
| Ohio | $69.77 | $209.30 | 19.38¢ |
| Oklahoma | $53.35 | $160.06 | 14.82¢ |
| Oregon | $57.31 | $171.94 | 15.92¢ |
| Pennsylvania | $78.37 | $235.12 | 21.77¢ |
| Rhode Island | $101.45 | $304.34 | 28.18¢ |
| South Carolina | $56.74 | $170.21 | 15.76¢ |
| South Dakota | $54.54 | $163.62 | 15.15¢ |
| Tennessee | $48.31 | $144.94 | 13.42¢ |
| Texas | $57.28 | $171.83 | 15.91¢ |
| Utah | $47.92 | $143.75 | 13.31¢ |
| Vermont | $85.82 | $257.47 | 23.84¢ |
| Virginia | $63.50 | $190.51 | 17.64¢ |
| Washington | $52.67 | $158.00 | 14.63¢ |
| West Virginia | $58.72 | $176.15 | 16.31¢ |
| Wisconsin | $69.88 | $209.63 | 19.41¢ |
| Wyoming | $51.95 | $155.84 | 14.43¢ |
How it works
The formula
kWh = watts × hours × days ÷ 1,000
cost = kWh × rate
Assumptions
- Constant-wattage cable draws its rating whenever it's on: Easy Heat ADKS is 5 W per foot at 120 V (a 120 ft cable is 600 W, a 240 ft one 1,200 W).
- Self-regulating cable draws more as it gets colder and wetter. Raychem IceStop GM-1XT is rated 12 W per foot in snow or ice at 32°F and about 5.5 W per foot in dry air, so 12 W per foot is the cost while it's actually melting. Your cable's data sheet gives its own figures.
- "Hours a day" is time it's switched on. A snow and temperature controller turns it on only when it's needed.
Worked example: 100 ft left on all winter
100 ft of 5 W-per-foot cable, on 24 hours a day for 3 months
- 100 × 5 = 500 W
- 500 W × 24 h × 30 days ÷ 1,000 = 360 kWh a month
- 360 kWh × 18.16¢ = $65.38 a month, $196.13 a winter
Ways to cut the cost
- Use a controller that senses snow and temperature, or a plug-in thermostat, instead of leaving it on all winter.
- Switch it on before a storm and off a day after the gutters drain.
- Fix the cause: ice dams come from attic heat melting the snow; more attic insulation and sealing air leaks can make the cable unnecessary.
- Plug it into a GFCI outlet and follow the maker's layout; constant-wattage cable must never cross itself.
Questions people ask
How much does roof heat cable cost to run?
About 9 cents an hour for 100 ft of 5 W-per-foot cable at the U.S. average of 18.16¢ per kWh (EIA, August 2026). Left on around the clock, that's $65.38 a month, from $45.79 in Nevada to $169.85 in Hawaii.
Should I leave heat tape on all winter?
You don't need to. Cable left on 24 hours a day costs $65.38 a month for 100 ft; on a snow-and-temperature controller that runs it about 8 hours a day, $21.79. Most makers recommend a controller or switching it on only when snow and freezing temperatures come together.
How many watts does heat cable use?
Constant-wattage roof cable like Easy Heat ADKS is 5 W per foot at 120 V, so a 120 ft cable is 600 W. Self-regulating cable changes with conditions: Raychem IceStop GM-1XT is rated 12 W per foot in snow or ice at 32°F and about 5.5 W per foot in dry air.
Is self-regulating cable cheaper to run?
Not necessarily. It draws less in dry cold air, but in the wet snow and ice it's there for it draws more per foot than constant-wattage cable: 100 ft at 12 W per foot left on all day is $156.90 a month. Its real advantages are that it can't overheat where it crosses itself and it can be cut to length.
How much cable do I need?
Easy Heat says to plan for the cable to zig-zag along the roof edge, drop into the gutter, run along it and go down the downspout. Use the length printed on the cable you buy; most come in fixed lengths from 30 to 240 ft.