Cubic Feet Per Minute (CFM)

By Anne Fonda

Cubic feet per minute (CFM) measures the volume of air that flows through the ductwork per minute. In HVAC, CFM airflow is important. It helps determine the correct size and capacity for your air conditioner, heat pump, and furnace, as well as your ductwork.   

Your HVAC system heats, cools, and moves air - that’s what the V in HVAC is all about -

ventilation. Having either too much or too little airflow can affect your comfort and potentially harm your ductwork and HVAC system components.

Good airflow is important for your HVAC system to function properly. It helps keep the air in your home clean and at a consistent temperature. The right CFM can improve indoor air quality (IAQ) as well as comfort.

The correct answer will depend on the size of your home. Larger homes will require a higher cubic foot per minute air flow rate. A typical central AC unit or heat pump can produce an average of 400 CFM per ton of air conditioning capacity.

So, as an example, a 1,200 CFM requirement would mean you need a 3-ton HVAC system. With a new HVAC installation or HVAC replacement, you will want the HVAC company to perform a Manual J Calculation to ensure proper sizing.

In a new installation, they should also use a CFM ductwork chart to properly size your air ducts.

If they are adding to your ductwork system in an HVAC zoning system or replacing ductwork, they should also refer to a ductwork CFM chart to help ensure proper airflow. They may also use a CFM calculator.

CFM is closely related to the air exchange rate or air changes per hour (ACH). ACH measures how many times the air in your home is fully replaced by fresh outdoor air or recirculated air each hour. In general, the higher the ACH, the better the indoor air quality.

This CFM chart shows some standard recommendations for the ACH in various rooms in your home.

DIY tips: Improve your air quality by using bathroom fans and range hoods/stove exhaust fans. Open windows when the weather and safety allow to help with ventilation. In addition, maintain your HVAC system airflow by changing the air filter every 30-90 days and keeping the outdoor unit clear on all sides.

Work with your local American Standard dealer to ensure your home gets the airflow it needs to maintain healthy indoor air quality. To maintain proper airflow, you’ll want to schedule regular HVAC maintenance as well.

A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need. 

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism. When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by Kimberly Sexton, Senior Systems Engineer