How Often Should You Change Your HVAC Air Filter?

If you’ve ever wondered, “How often should I change my air filter?” you’re not alone. Should you replace it every 30 days, 90 days, once a year, or somewhere in between? The truth is, there’s not a clear answer, as it varies based on several factors. HVAC.com breaks down how often you should replace your air filter and explains the key factors that influence the replacement schedule.

When Is the Right Time to Replace Your Air Filter?

To maintain optimal airflow and indoor air quality, it’s generally recommended to replace your air filter every 1 to 3 months. However, factors like the type of filter, indoor air quality, and whether you have pets can affect the ideal replacement frequency.

What Affects How Often You Need to Change Your HVAC Filter?

• Type of filter. The type of furnace filter you use affects how often you’ll need to replace it. Standard fiberglass filters usually last about 30 to 60 days, while pleated filters, which have an increased surface area, can go up to 90 days. Meanwhile, high-efficiency HEPA filters, known for their excellent air quality, might only need changing every 6 to 12 months.
• The filter’s thickness. The thickness of your HVAC filter also affects when you need to replace it. Thinner filters, usually around 1 inch thick, can clog up faster and might need changing every 1 to 3 months. Thicker, high-efficiency filters, between 4 to 5 inches, tend to last longer – usually 6 to 12 months – because they can hold more particles while keeping airflow steady.
• Dust and air quality levels. Homes can become excessively dusty due to factors like poor air filtration, inadequate ventilation, high levels of indoor activity, or pets that stir up dust and debris. All this dust makes its way to your HVAC filter, causing it to become clogged more quickly, requiring more frequent filter replacements to maintain optimal air quality and system performance. Smoke and other pollutants can also increase the rate in which you need to replace your air filters.
• Pets. We love our furry friends, but their hair and pet dander can significantly impact the efficiency of your HVAC system. Pet dander can quickly clog up HVAC filters, leading to reduced airflow and necessitating more replacements. Regularly changing your air filter helps maintain better air quality and system performance in homes with pets.
• HVAC usage. The frequency in which you use your heating and cooling system also affects how often your filter needs to be cleaned or replaced. If you live in an area with extreme temperatures, your HVAC system will run more often, leading to a shorter lifespan. In many parts of the country, homeowners typically change their filters more frequently during the winter and summer months than they do during the off-season.
• Home occupancy. When there are more people in the house, there’s usually higher levels of dust, dirt, and other particles coming in from outside, which can clog the filter faster. So, if you have several people living in your home, you might need to change your filters more often to keep the air clean and the HVAC system running efficiently.

Inspecting Your HVAC Filter

As you can see, the exact frequency in which you change your furnace filter may vary based on the time of year, how many people are currently living in your home, and other environmental factors. A good rule of thumb is to check your furnace filter once a month to assess its condition. After a few months, you’ll get a better idea of the right replacement interval.

If the filter looks dirty or clogged, it’s time to replace it to ensure your HVAC system continues to run efficiently. One way to determine if your air filter needs to be replaced is by holding it up to a light; if no light passes through it, it needs to be replaced.

You can also consult with your HVAC system’s owner’s manual about air filter maintenance and replacement frequency.