How regularly 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 around the residence
- Your MERV rating
For standard 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 replace 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 commonly sold 1" filter with a MERV rating of 4, you should be able to wait up to 90 days before changing it.
What air filter models survive longer?
Some air filters are manufactured to last up to six months, while others need to be replaced monthly. The more powerful the air filter, the longer it will last. In general, 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 eliminate 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 need to replace 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 exchange my air filter based on thickness?
The life span 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 advantages 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 filtering out the particles in your home. They also generate less air resistance, which can help your HVAC system perform more efficiently and minimize wear and tear on components such as 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 own pets, you might have to exchange your air filter more often. Pet hair and dander can quickly clog 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 without pets. The same goes for cats, even though 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.
Though a good rule of thumb, you will have to inspect your air filter more frequently to see if it needs to be replaced. 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 looks clogged.
Here are averages that might help you know how regularly you should get a new air filter at your home:
- 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