How frequently you should replace your air filters could 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 generally instruct you to replace them every 30–90 days. If you suffer from light to moderate allergies, you could install a better air filter or exchange 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 designed to last up to six months, while others must be replaced monthly. The denser the air filter, the longer it will last. As a whole, you should look at 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 assesses how well an air filter can remove particles from the air. The higher the MERV rating, the smaller the particle that will be captured by the air filter.
While a filter with a higher MERV rating will last longer, it could also restrict the airflow in your home. And you will have to exchange the filter more often. And if you own an older system, prepare to replace the filter more often to extend the life of your filter.
How often do I need to replace my air filter based on thickness?
The life span of an air filter also depends on its thickness. A 1" filter will need 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 benefits of thicker filters is not only do they perform longer, but they also have a better MERV rating. This means they will do a better job of getting rid of the particles in your home. They also produce less air resistance, which can help your HVAC system function more efficiently and decrease wear and tear on components including the blower motor.
If you have a whole-house air purifier, you will also need to replace the filters more frequently.
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 an air filter and reduce its effectiveness. For every shedding dog you have, prepare to replace the filter a month sooner than you would for a home without pets. The same goes for cats, although they don't shed as frequently as dogs. If you have a hypoallergenic or non-shedding dog or cat, you might not need to replace your air filter as often.
Although a good rule of thumb, you will have to examine your air filter more frequently to see if it needs to be exchanged. Dogs don't shed to the same extent year-round. They shed more in the spring and fall when they are blowing their coat. Examine the air filter monthly and replace it when it appears clogged.
Here are averages that may help you know how regularly you should get a new air filter at your residence:
- Vacation house or one occupant and no pets or allergies: every 6–12 months
- Everyday 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