How frequently you should replace your air filters can depend on the following:
- Air filter model
- Total indoor air quality
- Number of pets
- Household size
- Air pollution levels and construction near the residence
- Your MERV rating
For common 1"–3" air filters, manufacturers usually advise you to replace them every 30–90 days. If you suffer from light to moderate allergies, you could install a better air filter or swap them even more regularly.
The short answer to "how often should I replace my air filter?":
If you don't have a smoker or pets in the home, and your filter is the frequently sold 1" filter with a MERV rating of 4, you should be able to wait up to 90 days before replacing it.
What air filter models survive longer?
Some air filters are manufactured to last up to six months, while others must be replaced every month. The more powerful the air filter, the longer it will last. In general, you should check the thickness of the filter rather than the brand. You also need to look at the MERV rating.
The MERV rating is a scale that goes from 1-20 and calculates how effectively an air filter can pull particles from the air. The higher the MERV rating, the smaller the particle that will be caught by the air filter.
While a filter with a higher MERV rating will last longer, it may also interfere with the airflow in your home. And you will have to switch out the filter more often. And if you own an older system, plan to replace the filter more frequently to preserve the life of your filter.
How often do I need to exchange my air filter based on thickness?
The longevity of an air filter also depends on its thickness. A 1" filter will have to be replaced more often than a 4" filter.
- A 1" pleated air filter should be replaced every 30-60 days.
- A 2" pleated air filter should be replaced every 90 days.
- A 3” pleated air filter should be replaced every 120 days.
- A 4" pleated air filter should be replaced every 6 months.
- A 5” or 6" pleated air filter should be replaced every 9-12 months.
One of the perks of thicker filters is not only do they last longer, but they also have a higher MERV rating. This means they will do a better job of eliminating the particles in your home. They also create less air resistance, which can help your HVAC system run more efficiently and reduce wear and tear on components like the blower motor.
If you have a whole-house air purifier, you will also need to replace the filters more often.
How often should I change my air filter if I have a dog or cat?
If you have pets, you might need to exchange your air filter more often. Pet hair and dander can quickly clog up an air filter and lower its effectiveness. For every shedding dog you have, expect to replace the filter a month sooner than you would for a home with no pets. The same goes for cats, even though they don't shed as often as dogs. If you have a hypoallergenic or non-shedding dog or cat, you might not have to replace your air filter as often.
Though a good rule of thumb, you will need to examine your air filter more frequently to see if it needs to be exchanged. Dogs don't shed the same amount year-round. They shed more in the spring and fall when they are getting rid of their coat. Inspect the air filter monthly and replace it when it appears clogged.
Here are averages that might help you know how often you should get a new air filter at your residence:
- Vacation house or one occupant and no pets or allergies: every 6–12 months
- Ordinary suburban home without pets: every 90 days
- One dog or cat: every 60 days
- More than one pet or if anyone has allergies: 20–45 days