How much does it cost to run an attic fan?
An attic fan drawing 300 watts, used 8 hours a day, uses about 2.40 kWh per day and costs about $0.47 per day, $14.18 per month, and $170.03 per year at the US average residential rate of 19.4¢/kWh. Enter your own wattage, hours, and state below for an exact figure.
Estimates only — based on typical wattages and average state rates, not your actual bill.
What drives the cost
An attic or whole-house fan uses a fraction of what air conditioning does, exhausting hot air and pulling cooler outside air in. It only helps when the outside air is actually cooler than inside, which makes it an evening and overnight tool rather than an afternoon one. Used correctly it can displace hours of compressor run time.
Cost at different daily usage
Same attic fan at 300 watts, run for different amounts of time, at 19.4¢/kWh.
| Usage | kWh/day | Per day | Per month | Per year |
|---|---|---|---|---|
| 4 h/day | 1.20 kWh | $0.23 | $7.09 | $85.02 |
| 8 h/day | 2.40 kWh | $0.47 | $14.18 | $170.03 |
| 12 h/day | 3.60 kWh | $0.70 | $21.27 | $255.05 |
| 16 h/day | 4.80 kWh | $0.93 | $28.36 | $340.06 |
Cost by model power draw
Not all models are equal. At 8 h/day, here is what the range costs.
| Model | Power | kWh/day | Per day | Per month |
|---|---|---|---|---|
| Low-draw model | 150 W | 1.20 kWh | $0.23 | $7.09 |
| Typical | 300 W | 2.40 kWh | $0.47 | $14.18 |
| High-draw model | 700 W | 5.60 kWh | $1.09 | $33.09 |
Cost by state
An attic fan at 300 W for 8 h/day, priced at each state's average residential rate.
| State | Rate | Per day | Per month | Per year |
|---|---|---|---|---|
| Alabama | 16.8¢ | $0.40 | $12.25 | $146.91 |
| Alaska | 28.2¢ | $0.68 | $20.62 | $247.29 |
| Arizona | 15.2¢ | $0.37 | $11.13 | $133.41 |
| Arkansas | 14.4¢ | $0.34 | $10.49 | $125.79 |
| California | 33.2¢ | $0.80 | $24.29 | $291.27 |
| Colorado | 16.2¢ | $0.39 | $11.81 | $141.56 |
| Connecticut | 27.4¢ | $0.66 | $20.00 | $239.76 |
| Delaware | 19.4¢ | $0.47 | $14.16 | $169.77 |
| District of Columbia | 25.4¢ | $0.61 | $18.56 | $222.50 |
| Florida | 15.2¢ | $0.36 | $11.08 | $132.89 |
| Georgia | 15.8¢ | $0.38 | $11.57 | $138.76 |
| Hawaii | 52.0¢ | $1.25 | $37.99 | $455.52 |
| Idaho | 12.3¢ | $0.30 | $9.02 | $108.19 |
| Illinois | 23.9¢ | $0.57 | $17.42 | $208.93 |
| Indiana | 18.1¢ | $0.44 | $13.26 | $158.99 |
| Iowa | 14.1¢ | $0.34 | $10.33 | $123.87 |
| Kansas | 15.1¢ | $0.36 | $11.05 | $132.54 |
| Kentucky | 15.0¢ | $0.36 | $10.94 | $131.22 |
| Louisiana | 14.2¢ | $0.34 | $10.34 | $123.95 |
| Maine | 28.6¢ | $0.69 | $20.92 | $250.80 |
| Maryland | 21.8¢ | $0.52 | $15.90 | $190.71 |
| Massachusetts | 28.8¢ | $0.69 | $21.05 | $252.46 |
| Michigan | 22.0¢ | $0.53 | $16.08 | $192.81 |
| Minnesota | 16.9¢ | $0.41 | $12.38 | $148.48 |
| Mississippi | 16.2¢ | $0.39 | $11.81 | $141.56 |
| Missouri | 13.7¢ | $0.33 | $9.99 | $119.84 |
| Montana | 14.7¢ | $0.35 | $10.72 | $128.51 |
| Nebraska | 13.6¢ | $0.33 | $9.93 | $119.05 |
| Nevada | 13.6¢ | $0.33 | $9.94 | $119.14 |
| New Hampshire | 27.3¢ | $0.66 | $19.97 | $239.41 |
| New Jersey | 23.3¢ | $0.56 | $17.00 | $203.85 |
| New Mexico | 14.1¢ | $0.34 | $10.32 | $123.69 |
| New York | 29.9¢ | $0.72 | $21.87 | $262.19 |
| North Carolina | 15.1¢ | $0.36 | $11.02 | $132.19 |
| North Dakota | 13.6¢ | $0.33 | $9.94 | $119.22 |
| Ohio | 19.5¢ | $0.47 | $14.26 | $171.00 |
| Oklahoma | 13.4¢ | $0.32 | $9.77 | $117.21 |
| Oregon | 16.3¢ | $0.39 | $11.89 | $142.53 |
| Pennsylvania | 21.6¢ | $0.52 | $15.74 | $188.78 |
| Rhode Island | 29.5¢ | $0.71 | $21.52 | $258.07 |
| South Carolina | 16.2¢ | $0.39 | $11.82 | $141.74 |
| South Dakota | 15.7¢ | $0.38 | $11.49 | $137.79 |
| Tennessee | 14.5¢ | $0.35 | $10.57 | $126.76 |
| Texas | 16.4¢ | $0.39 | $12.01 | $144.01 |
| Utah | 13.0¢ | $0.31 | $9.47 | $113.53 |
| Vermont | 24.9¢ | $0.60 | $18.18 | $218.04 |
| Virginia | 17.6¢ | $0.42 | $12.87 | $154.26 |
| Washington | 14.9¢ | $0.36 | $10.92 | $130.96 |
| West Virginia | 16.8¢ | $0.40 | $12.27 | $147.17 |
| Wisconsin | 19.7¢ | $0.47 | $14.42 | $172.92 |
| Wyoming | 14.8¢ | $0.36 | $10.81 | $129.65 |
How to cut the cost
- Run it when outdoor air is cooler than indoor air, typically evening and early morning.
- Open windows in the rooms you want cooled — the fan needs makeup air or it just depressurizes the house.
- Never run it at the same time as the air conditioner; you are paying to exhaust conditioned air.
- Close it up and insulate the housing in winter to avoid a large heat leak.
Compare with related appliances
Monthly cost at typical usage and 19.4¢/kWh.
Questions
Is an attic fan cheaper than air conditioning?
Substantially — it uses a small fraction of the power. The catch is that it only works when outside air is cooler, so it supplements rather than replaces AC.
How do you calculate what an attic fan costs to run?
Multiply its wattage by the hours it runs per day, divide by 1,000 to get kilowatt-hours, then multiply by your electricity rate. For an attic fan: 300 W × 8 h ÷ 1,000 = 2.40 kWh per day, which at 19.4¢/kWh is $0.47 per day.
How many watts does an attic fan use?
Typically 300 watts, with most models falling between 150 and 700 watts. The label on the appliance or its power supply gives the figure for your specific unit.