Is a whole-house fan expensive to run?

Run it after sunset when outside air is cooler than inside, then close up the house in the morning. At typical use it adds about $6.02 to a monthly electric bill at the US-average rate, but that swings from $4.20 in the cheapest states to $15.64 in the most expensive.

How many watts does a whole-house fan use?

Whole-House Fan typically draws about 400 running watts. Because it has a motor or compressor, it briefly spikes to around 900 watts at startup, which matters for generator and breaker sizing but not for energy cost. Check the nameplate or label on your specific unit for its exact rating.

How much electricity (kWh) does a whole-house fan use?

At typical use (400 W for 3 hours a day), a whole-house fan uses about 1.2 kWh per day — roughly 37 kWh per month, or about 4% of what the average US home uses in a month (863 kWh). Energy used doesn't depend on your electricity rate — only the bill does.

How can I lower the cost of running a whole-house fan?

Run it after sunset when outside air is cooler than inside, then close up the house in the morning. You can also cut the cost by lowering your electricity rate — many utilities offer cheaper off-peak hours — or simply by running it fewer hours. The calculator on this page shows how changing hours per day or your electricity rate moves the number.

How Much Does It Cost to Run a Whole-House Fan?

A whole-house fan swaps hot indoor air for cool evening air at a tenth of central AC's draw. At the US-average rate of 16.5¢/kWh, running a whole-house fan costs about $6.02/month ($72.18/year) at typical use. Adjust the watts, hours, and your rate below for your exact number.

Power (watts)

Hours per day: 3

Days per week: 7

Your state (sets the rate)

Electricity rate ($/kWh)

Cost to run a whole-house fan

$72/yr

Per day: $0.20
Per month: $6.02
Energy per year: 438 kWh

Cost = power (kW) × hours × days × your rate. Defaults are typical values — enter your appliance's actual watts (often on a label) and your real rate for a precise figure.

How much electricity does a whole-house fan use?

At 400 W for 3 hours a day, a whole-house fan uses about 1.2 kWh per day — roughly 37 kWh per month and 438 kWh per year. That's about 4% of the 863 kWh the average US home uses in a month. Energy use is the same everywhere — only the price per kWh changes your bill.

Wondering about the circuit instead? See how many amps a whole-house fan draws.

Cost to run a whole-house fan by electricity rate

Same 400 W appliance, 3 h/day — the bill changes with where you live.

Scenario	Rate	Per month	Per year
Cheapest states (North Dakota)	11.5¢	$4.20	$50.41
US average	16.5¢	$6.02	$72.18
Most expensive (Hawaii)	42.9¢	$15.64	$187.73

Find your state's rate on the electricity rates by state page, or see the appliance wattage chart for more devices.

Frequently asked questions

At the US-average residential rate of 16.5¢/kWh, a whole-house fan drawing 400 watts for about 3 hours a day costs roughly $0.20 per day, $6.02 per month, and $72.18 per year. Your actual cost depends on your electricity rate and how much you use it, and the calculator on this page adjusts for both.

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How Much Does It Cost to Run a Whole-House Fan?

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Cost to run a whole-house fan by electricity rate

Frequently asked questions