What Size Whole-House Fan Do I Need?

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Updated August 16, 2022

If you’re shopping for an energy-efficient fan with adequate cooling power for your home, you may wonder, “What size whole-house fan do I need?” Whole-house fans feature attic ventilation and ducts in your ceiling, similar to a central air conditioner. For whole-house ventilation, you need the correct system size for the square footage of your living space. Luckily, you can easily calculate the best size whole-house fan and enjoy comfortable temperatures for your entire household.


  • Whole-house fans feature built-in ducts and fans that cycle fresh air into your home and expel stale or warm air.
  • Experts recommend 2 CFM per square foot of living space for adequate airflow exchanges and cooling.
  • You can maximize your whole-home fan’s cooling power by running it during nighttime.

If you’re curious about the house-cooling power of whole-house ventilation, consider reading our guide to what a whole-house fan is. You can also learn about the top-rated ventilation fans for your home system and consider looking at the strongest wall-mount fans for additional venting.

Insider Tip

You can quickly lower the air temperature in your space by closing the windows and doors to rooms that don’t require cooling.

How to Size a Whole-House Fan

To effectively lower the temperature in your home means you must find the right house fan. Whole-home units feature air vent fans contributing to air exchanges in your home. Luckily, experts rate fan systems for their ability to move air which directly relates to your air exchange time.

A fan’s CFM rating references its ability to move air in cubic feet per minute (CFM). Ensuring you have the correct CFM rating will provide adequate airflow throughout your home.


Your attic venting, fan airflow, and air quality will suffer if you do not consistently dust your wall vents.

How to Calculate the Correct Size House Fan

Experts recommend about two CFM per square foot of your home. So, measure the square footage of your cooling space and multiply that number by two. For example, if you live in a 1500 sq. ft. home, you want a fan airflow CFM of 3000. If you want to turn over more air per minute, you can multiply the square feet of your space by 3. That said, experts do not recommend more CFM of air volume than that.

STAT: A US EIA (Energy Information Agency) showed that 8.2% of American homeowners use a whole-house fan solution for cooling. (source)

What Size Whole-House Fan Do I Need FAQs

What’s the difference between attic vents and whole-house fans?

Attic venting releases hot air as it rises to the top level of your home and attic space. A whole-home fan system features built-in ducts like a central air conditioning unit. In addition, house fans offer a series of fans that force stale and warm air from your space while bringing in fresh, cool air from outside.

Can I run a whole house fan all night?

You can run a house fan system at any time of the day. Experts recommend running your whole-house fan at night to bring cool air into your home. This fan system works best when outdoor temperatures are lower than indoor space.

How energy efficient are whole house fans?

These units are a massive energy saver compared to traditional air conditioning. For example, the average whole-home fan system uses 200 to 700 watts while the average AC unit uses 2000 to 5000 watts. Switching from AC to a whole-home fan would take your cooling bill from $100 to under $10.
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