How Often Should You Change Your Air Filter in Your Home?


If the air filters in your home are dirty, clogged, or old, it’s detrimental to your indoor air quality. Most people already know that air filters should be changed regularly to keep systems running smoothly and maintain optimal air quality. But what does “regularly” mean for your system? It’s different for every household, and this guide will help you determine your answer.

dirty air filter next to clean one

What type of air filter should you use?

The first determining factor for figuring out how frequently to change your filter is the type of filter your HVAC system uses. Two types of filters are available to homeowners: fiberglass and pleated air filters. Although both filter types are disposable, there are some essential differences between them.

  • Fiberglass air filters are generally less expensive than pleated filters, but they are also less efficient at capturing dust and particles in the air. Therefore, you should replace a fiberglass air filter every 30 days.
  • Pleated air filters are more expensive to purchase than fiberglass filters, but they trap particles more efficiently and only need to be changed every 90 days, depending on how much the system is being used.

When you purchase a new air filter, the packaging lists a recommended replacement schedule. Some filter manufacturers even offer subscription services that deliver new filters to your home on a set schedule. This is convenient for people who need help remembering to check and replace filters.

The Size of Your Home

The size of your home greatly impacts how often you should change your air filter. Larger homes circulate more air through their HVAC system, so the filter gets dirtier faster and demands more frequent replacement. HVAC systems in smaller homes circulate less air, so the filters can last longer. However, small spaces sometimes have smaller appliances, and smaller filters must be changed more often. 

Your Outdoor Air Quality

Outside pollutants and contaminants can seep inside your home and clog your air filter—especially if you live in a large city with traffic pollution. Wildfire smoke can also have a similar impact on your air filter, causing it to clog more rapidly and requiring more frequent replacement.

Your Pets

Pets truly make a house a home. But they also impact your indoor air quality. Pets with fur—like cats and dogs—shed a substantial amount of hair and release dander into the air. They also track dirt, pollen, mold, and other contaminants from outside. If you have pets in your home, check your air filter each month, and replace it when it’s dirty.

Your Allergies

Allergy sufferers should be extra diligent about checking and replacing the air filters in their homes. You can significantly reduce allergy symptoms by using a high-quality air filter and adopting a more frequent filter replacement schedule. Excess dust, pet dander and other allergens floating around in your indoor air amplify allergy symptoms like coughing, sneezing, and a runny nose. To ensure that only clean air leaves your HVAC system, change your air filter before it becomes clogged.


During the mild seasons (spring and fall), people use their HVAC system less than in extreme summer and winter conditions. When you use your air conditioning or heating less, the air filter takes longer to get dirty and doesn’t need to be changed as frequently. However, during mild seasons, the number of contaminants in your home may increase and worsen allergy symptoms because your HVAC system isn’t circulating the air, and the filter isn’t trapping any particles. You can improve your indoor air quality by turning on your thermostat’s fan (switching it from AUTO to ON). This way, the fan cycles your air through the filter without heating or cooling. If you run your fan during spring and fall, your air filter will need the same replacement schedule as summer and winter.

Indoor Air Quality Services in Knoxville

You can breathe easy with Chancey & Reynolds. We ensure healthy, high-quality, comfortable indoor air for your home and business. We provide quick and efficient HVAC system installation, repair, and maintenance throughout the greater Knoxville area, ensuring your indoor quality is always clean and consistent.

Air conditioning and heating system maintenance are just one part of Chancey & Reynolds’ comprehensive HVAC services. We’ve been installing, maintaining, and repairing HVAC systems in greater Knoxville since 1978. HVAC users across Knoxville and Lenoir City trust our team of air specialists to keep their homes comfortable all year long. Contact us today to get started!