How Much Does a Whole House Fan Cost to Run? (2026 Data)

A 450-watt whole-house fan draws 0.45 kWh for every hour it runs, which works out to about 8 cents an hour at the US average rate from the EIA Electric Power Monthly. Unlike an air conditioner, the fan draws its full wattage the whole time it's on. There's no compressor cycling on and off, so the math is clean: watts, times hours, times rate.

On a typical schedule of six hours an evening, that's 2.7 kWh, or about 49 cents a day and $15 a month. Run it lighter, four hours for an evening pull-down and a pre-dawn flush, and it drops to about $10. Run it all night at eight hours and it climbs to about $20. Across a five-month May-to-September season at the six-hour pattern, the fan adds roughly $73 to the year's electricity.

The reason a whole-house fan exists is the power difference. A central air conditioner runs a 3,500-watt compressor to squeeze heat out of refrigerant. A whole-house fan runs a 450-watt motor to pull cool outside air through the house and push hot air out through the attic. That's about an eighth the power for the hours both are running, or 87 percent less. A smaller 200-watt fan draws 94 percent less than the AC compressor.

On the bill, a central AC costs about 32 cents an hour at half duty cycle and 63 cents at full tilt. The whole-house fan's 8 cents sits at a quarter to an eighth of that. Held to the same six hours, the fan costs about $15 a month against the AC's $57, a difference of $42. Over the summer season that's roughly $210 left on the table for any home that can run the fan instead of the compressor. The mechanism is straightforward ventilation cooling, described by the US Department of Energy: open windows let cool outdoor air in, the fan exhausts the day's heat out the roof, and the house drops to the outdoor temperature within an hour.

Search results mix these three together, and they do different jobs at different costs. A ceiling fan draws about 60 watts and costs around $4 a month at twelve hours a day, the way most people run one. It moves air across your skin so a warm room feels cooler, but it does nothing to the actual air temperature. Turn it off when you leave the room.

An attic fan draws about 300 watts and costs around $6 a month, because it runs on a thermostat that cycles it off once the attic cools, so it logs closer to four effective hours a day than six. It exhausts hot air from the attic only, which lowers the heat load pressing down on the living space below. A whole-house fan draws about 450 watts and, run flat out for the full six evening hours, costs around $15 a month. It's the only one of the three that lowers the temperature of the air you actually breathe. It pulls the whole house full of cool outside air. The higher cost buys a different result.

A whole-house fan earns its keep in dry climates with cool evenings. California's Central Valley, Colorado, Nevada, high-desert Arizona, and the inland Pacific Northwest all swing 25 to 40 degrees between afternoon and night. The fan flushes the house in the evening, the structure holds the cool through the next morning, and the AC stays off for hours it would otherwise run.

In the humid Southeast the math reverses. Florida, the Texas Gulf coast, Houston, and Atlanta stay warm and sticky overnight. Pulling in 78°F humid air doesn't cool the house, and the moisture it carries becomes a latent load the air conditioner has to remove later, so the fan can cost more than it saves. Two rules decide whether it works at all: run it only when the outdoor temperature is below the indoor temperature, and open two to four windows so the fan has air to pull. A whole-house fan running against closed windows moves no air and cools nothing, which is where most complaints about them come from.

Whole-house fans run from about 200 watts for a small insulated-damper unit to 800 watts for a large two-speed model, with 450 watts typical. At six hours a day, that range runs from about $6.50 a month at 200 watts to $26 a month at 800 watts.

Common residential models land in the lower half of that range. The QuietCool QC CL-4700 at 360 watts costs about $12 a month. The Tamarack HV1600 at 320 watts runs about $10. The Air Vent 54301 at 500 watts runs about $16. Bigger fans move more air and cool the house faster, so they reach the target temperature in fewer minutes. The higher nameplate wattage is the price of a quicker flush, not a less efficient motor.

A 450-watt fan on a six-hour summer schedule uses about 81 kWh a month wherever it sits. The state rate is the only variable:

Louisiana (12.44¢/kWh): $10. Texas (14.80¢/kWh): $12. US average (18.05¢/kWh): $15. New York (24¢/kWh): $19. California (33.75¢/kWh): $27. Hawaii (39.89¢/kWh): $32.

The most useful state on this list is California. Its dry inland nights are exactly the conditions a whole-house fan needs, and its 33.75-cent rate makes every hour of avoided air conditioning expensive. The fan costs more to run there than in Louisiana, but each hour it keeps the AC off is worth more too. Every state's 2026 residential rate is in the state rates guide.

Treat a whole-house fan as a partial replacement for air conditioning, not another load stacked on top. In the right climate it shifts cooling hours off a 3,500-watt compressor and onto a 450-watt motor, which is why it shows up in most lists of ways to lower a summer electric bill. It sits in the same decision as the broader fan versus air conditioner tradeoff: fans win on cost everywhere, and lose the moment the outdoor air is no longer cool enough to do the job.

These numbers use a 450-watt fan and a six-hour evening schedule. Your fan's wattage, how many hours it runs, and your state rate all move the result. The whole-house fan calculator takes your fan's draw and your state and returns the monthly and yearly cost. If the summer bill climbed and you're trying to work out what's driving it, the why your electric bill is high walkthrough helps isolate the load.