How often you need to exchange 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 nearby the residence
- The MERV Rating
For basic 1"–3" air filters, companies typically tell you to exchange them every 30–90 days. If you suffer from mild to moderate allergies, you could use a better air filter or exchange them even more frequently.
The quick answer to "how often do I have to change the air filter?":
If you don't have a smoker or pets at 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 prior to replacing it.
What air filter styles last longer?
Many air filters are supposed to survive up to six months, while others need to be switched each month. The denser the air filter, the longer it will last. Overall, you should check the thickness of the filter rather than the brand. You also need to check at the MERV Rating.
The MERV Rating is a scale that records from 1-20 and assesses how well an air filter will pull particles out of the air. The better the MERV Rating, the smaller the particle that can be caught by your air filter.
While a filter with a higher MERV Rating might last longer, it may also interfere with the flow of air in your home. And you will have to replace the filter more frequently. And if you acquire an older system, plan to replace the filter more frequently to conserve the life of your filter.
How often do I need to substitute my air filter based on thickness?
The lifespan of an air filter also relies on the thickness. A 1" filter will have to be changed out more frequently compared to a 4" filter.
- A 1" pleated air filter should be replaced every 30-60 days.
- A 2" pleated air filter must be switched every 90 days.
- A 3” pleated air filter must be replaced every 120 days.
- A 4" pleated air filter ought to be swapped out every 6 months.
- A 5” or 6" pleated air filter should be swapped every 9-12 months.
One of the advantages of thicker filters is not only do they last longer, but they also posses a better MERV Rating. This means they can do a better job of filtering out the particles in your home. They also generate less air resistance, which can help ones HVAC system operate more proficiently and limit strain on components including the blower motor.
If you own a whole-house air purifier, you will also need to exchange the filters more often.
How often should I exchange my air filter if I own a dog or cat?
If you want pets, you might need to switch out your air filter more often. Pet hair and dander can easily clog an air filter and reduce its effectiveness. For each shedding dog you have, expect to exchange the filter a month earlier than you would for a home lacking pets. The same goes for cats, although they don't shed as heavily as dogs. If you have a hypoallergenic or non-shedding dog or cat, you might not need to replace your air filter as much.
Even though it's a good rule of thumb, you might want to check on your air filter more often to see if it needs to be replaced. Dogs tend not to shed the same amount year-round. They shed more in the spring and fall when they are blowing their coat. Check the air filter monthly and change it when it seems clogged.
Here are averages that might help you recognize how often you should put in a new air filter at your residence:
- Vacation house or an individual occupant and no pets or allergies: every 6–12 months
- Standard suburban home without pets: every 90 days
- One dog or cat: every 2 months
- More than one pet or if a member of your family has allergies: 20–45 days