How regularly you need to replace your air filters could rely on the following:
- Air filter type
- Overall indoor air quality
- Number of pets
- Household size
- Air pollution levels and construction surrounding the residence
- Your MERV Rating
For common 1"–3" air filters, manufacturers usually ask you to change them every 30–90 days. If you suffer from light to moderate allergies, you can put in a better air filter or exchange them even more frequently.
The quick answer to "how often do I have to exchange my air filter?":
If you don't have a smoker or pets in your home, and your filter is the widely sold 1" filter with a MERV rating of 4, you should be able to wait up to 90 days prior to changing it.
What air filter styles last longer?
Some air filters are designed to survive up to six months, while others have to be switched month-to-month. The denser the air filter, the longer it can last. Generally, you should look at the thickness of the filter instead of the brand. You also need to take a look at the MERV Rating.
The MERV Rating is a scale that goes from 1-20 and measures how effectively an air filter should remove 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 should last longer, it could also impede the ventilation in your home. And you will have to replace the filter more frequently. And if you acquire an older piece of equipment, plan to exchange the filter more frequently to extend the life of your filter.
How frequently do I need to replace my air filter based on thickness?
The longevity of an air filter also hinges on its thickness. A 1" filter will have to be exchanged more frequently than a 4" filter.
- A 1" pleated air filter should be changed out every 30-60 days.
- A 2" pleated air filter should be switched every 3 months.
- A 3” pleated air filter ought to be exchanged every 4 months.
- A 4" pleated air filter ought to be changed 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 will do a superior job of eliminating the particles in your home. They also generate less air resistance, which can help an HVAC system operate more proficiently and limit strain on components like the blower motor.
If you own a whole-house air purifier, you will also need to switch out the filters more regularly.
How regularly should I replace my air filter if I have a dog or cat?
If you own pets, you might need to replace your air filter more often. Pet hair and dander can easily clog an air filter and reduce its effectiveness. For every shedding dog you have, expect to switch out the filter a month sooner than you would for a home with no pets. The same goes for cats, although they usually do not shed as heavily as dogs. If you have a hypoallergenic or non-shedding dog or cat, you might not have to replace your air filter as frequently.
Although a good rule of thumb, you will need to check the air filter more regularly to decide if it has to be swapped out. Dogs tend not to shed the same amount all year. They shed more in the spring and fall when they are blowing their coat. Take a look at the air filter monthly and change it when it appears clogged.
Here are averages that may help you recognize how frequently you should install a new air filter at your residence:
- Vacation house or an individual occupant and no pets or allergies: every 6–12 months
- Average suburban home without pets: every 90 days
- A single dog or cat: every 60 days
- More than one pet or if someone has allergies: 20–45 days