How much does it cost to run an attic fan?
An attic fan costs about 3.8¢ per hour, 30¢ a day, $9.20 a month and $46 a year at typical use (8 hours a day for 5 months a year) and the U.S. average rate of 17.99¢/kWh. Powered attic ventilators draw about 200-400 W. They can pull conditioned air out of the house through ceiling leaks, sometimes increasing AC use.
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Cost by hours of use
| Hours per day | kWh/day | Per day | Per month | Per year (all year) |
|---|---|---|---|---|
| 1 hour | 0.21 | 3.8¢ | $1.15 | $14 |
| 2 hours | 0.42 | 7.6¢ | $2.30 | $28 |
| 4 hours | 0.84 | 15¢ | $4.60 | $55 |
| 8 hours | 1.68 | 30¢ | $9.20 | $110 |
| 12 hours | 2.52 | 45¢ | $13.80 | $166 |
| 24 hours | 5.04 | 91¢ | $27.60 | $331 |
Cost to run an attic fan in every state
The same attic fan costs $31 a year in North Dakota and $111 in Hawaii, at each state's average residential rate (12 months ending July 2026).
| State | Rate | Per hour | Per month | Per year |
|---|---|---|---|---|
| North Dakota | 12.32¢ | 2.6¢ | $6.30 | $31 |
| Idaho | 12.65¢ | 2.7¢ | $6.47 | $32 |
| Nebraska | 12.86¢ | 2.7¢ | $6.58 | $33 |
| Louisiana | 12.99¢ | 2.7¢ | $6.64 | $33 |
| Utah | 13.32¢ | 2.8¢ | $6.81 | $34 |
| Nevada | 13.36¢ | 2.8¢ | $6.83 | $34 |
| Arkansas | 13.43¢ | 2.8¢ | $6.87 | $34 |
| Tennessee | 13.56¢ | 2.8¢ | $6.93 | $35 |
| Oklahoma | 13.70¢ | 2.9¢ | $7.01 | $35 |
| Montana | 13.84¢ | 2.9¢ | $7.08 | $35 |
| Kentucky | 13.92¢ | 2.9¢ | $7.12 | $36 |
| Missouri | 13.95¢ | 2.9¢ | $7.13 | $36 |
| Wyoming | 14.01¢ | 2.9¢ | $7.16 | $36 |
| Washington | 14.12¢ | 3.0¢ | $7.22 | $36 |
| Iowa | 14.13¢ | 3.0¢ | $7.23 | $36 |
| South Dakota | 14.20¢ | 3.0¢ | $7.26 | $36 |
| Mississippi | 14.77¢ | 3.1¢ | $7.55 | $38 |
| North Carolina | 14.77¢ | 3.1¢ | $7.55 | $38 |
| Kansas | 15.09¢ | 3.2¢ | $7.72 | $39 |
| Georgia | 15.12¢ | 3.2¢ | $7.73 | $39 |
| New Mexico | 15.32¢ | 3.2¢ | $7.83 | $39 |
| Florida | 15.39¢ | 3.2¢ | $7.87 | $39 |
| Arizona | 15.40¢ | 3.2¢ | $7.87 | $39 |
| West Virginia | 15.48¢ | 3.3¢ | $7.92 | $40 |
| Oregon | 15.50¢ | 3.3¢ | $7.93 | $40 |
| South Carolina | 15.64¢ | 3.3¢ | $8.00 | $40 |
| Texas | 15.96¢ | 3.4¢ | $8.16 | $41 |
| Minnesota | 16.22¢ | 3.4¢ | $8.29 | $41 |
| Alabama | 16.44¢ | 3.5¢ | $8.41 | $42 |
| Virginia | 16.48¢ | 3.5¢ | $8.43 | $42 |
| Colorado | 16.58¢ | 3.5¢ | $8.48 | $42 |
| Indiana | 16.94¢ | 3.6¢ | $8.66 | $43 |
| Delaware | 17.79¢ | 3.7¢ | $9.10 | $45 |
| Ohio | 18.25¢ | 3.8¢ | $9.33 | $47 |
| Wisconsin | 18.74¢ | 3.9¢ | $9.58 | $48 |
| Illinois | 18.79¢ | 3.9¢ | $9.61 | $48 |
| Pennsylvania | 20.70¢ | 4.3¢ | $10.58 | $53 |
| Maryland | 21.03¢ | 4.4¢ | $10.75 | $54 |
| Michigan | 21.05¢ | 4.4¢ | $10.76 | $54 |
| New Jersey | 23.78¢ | 5.0¢ | $12.16 | $61 |
| Vermont | 23.80¢ | 5.0¢ | $12.17 | $61 |
| District of Columbia | 24.20¢ | 5.1¢ | $12.37 | $62 |
| New Hampshire | 26.67¢ | 5.6¢ | $13.64 | $68 |
| Alaska | 26.85¢ | 5.6¢ | $13.73 | $69 |
| Connecticut | 27.99¢ | 5.9¢ | $14.31 | $72 |
| New York | 28.39¢ | 6.0¢ | $14.52 | $73 |
| Rhode Island | 29.27¢ | 6.1¢ | $14.97 | $75 |
| Maine | 29.31¢ | 6.2¢ | $14.99 | $75 |
| Massachusetts | 30.43¢ | 6.4¢ | $15.56 | $78 |
| California | 32.99¢ | 6.9¢ | $16.87 | $84 |
| Hawaii | 43.51¢ | 9.1¢ | $22.25 | $111 |
How to cut the cost
- Set the attic fan thermostat to 110-115°F instead of 90-100°F so it runs only on the hottest afternoons.
- Air-seal ceiling penetrations (lights, attic hatch, plumbing) before relying on an attic fan.
- Add attic insulation to R-38 to R-49; it reduces heat gain more than ventilation does.
- Consider passive ridge and soffit vents instead if the fan runs most of the day.
Cheaper ways to get the job done
Runs on its own solar panel with no grid electricity.
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Compare with similar appliances
| Appliance | Watts | Typical use | Per month | Per year |
|---|---|---|---|---|
| Attic fan | 300 | 8 hours a day for 5 months a year | $9.20 | $46 |
| Whole house fan | 300 | 5 hours a day for 5 months a year | $8.21 | $41 |
| Central air conditioner | 3,500 | 12 hours a day for 5 months a year | $103 | $517 |
| Window fan | 60 | 8 hours a day for 5 months a year | $2.63 | $13 |
| Bathroom exhaust fan | 15 | 1 hour a day | $0.08 | $1 |
| Warm mist humidifier | 300 | 8 hours a day for 5 months a year | $9.20 | $46 |
| Drum fan | 250 | 4 hours a day, 4 days a week for 5 months a year | $3.13 | $16 |
Head-to-head comparisons
Frequently asked questions
How much does it cost to run an attic fan per hour?
An attic fan drawing 300 watts uses 0.21 kWh per hour while running (70% duty cycle). At the U.S. average of 17.99¢/kWh that's 3.8¢ per hour. In North Dakota (12.32¢) it's 2.6¢. In Hawaii (43.51¢) it's 9.1¢.
How much does it cost to run an attic fan per month?
At typical use (8 hours a day for 5 months a year), an attic fan costs about $9.20 a month while in use and $46 a year over the 5 months it's typically used, at the U.S. average rate. Enter your ZIP in the calculator above for your utility's rate.
How many watts does an attic fan use?
Most attic fans use 100 to 500 watts. Check the label on the back or bottom for your model's exact rating.
How many kWh does an attic fan use?
About 1.68 kWh a day and 256 kWh a year at typical use (8 hours a day for 5 months a year).
Does an attic fan use a lot of electricity?
No. At about 256 kWh a year it's a small share (2.4%) of the average U.S. home's 10,492 kWh.
Is it cheaper to run an attic fan or a whole house fan?
At typical use, an attic fan costs about $46 a year versus $41 for a whole house fan. So the whole house fan is cheaper by about $5 a year. Use the comparison table above to compare them at your own settings.
How can I lower the cost of running an attic fan?
- Set the attic fan thermostat to 110-115°F instead of 90-100°F so it runs only on the hottest afternoons.
- Air-seal ceiling penetrations (lights, attic hatch, plumbing) before relying on an attic fan.
- Add attic insulation to R-38 to R-49; it reduces heat gain more than ventilation does.
Rates updated 2026-10-21: EIA data through July 2026. Typical wattage and usage reviewed against DOE, ENERGY STAR and manufacturer specs. Methodology.