How frequently you need to change the air filters could depend on the following:
- Air filter design
- Overall indoor air quality
- Number of pets
- Household size
- Air pollution levels and construction near the residence
- The MERV Rating
For basic 1"–3" air filters, brands usually tell you to change them every 30–90 days. If someone in your family suffers from mild to moderate allergies, you could put in a better air filter or exchange them even more regularly.
The short answer to "how often do I have to change my air filter?":
If you don't have a smoker or pets in your home, and the filter is the often 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 survive longer?
Many air filters are designed to survive up to six months, while others have to be replaced each month. The thicker the air filter, the longer it will last. Generally, you can examine the thickness of the filter instead of the brand. You also need to consider at the MERV Rating.
The MERV Rating is a scale that stretches from 1-20 and assesses how well an air filter can pull particles from the air. The higher 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 hamper the flow of air in your home. And you will need to replace the filter more regularly. And if you have an older system, plan to switch out the filter more often to conserve the quality of your filter.
How often should I substitute my air filter based on thickness?
The longevity of an air filter also counts on the thickness. A 1" filter will have to be exchanged more often instead of a 4" filter.
- A 1" pleated air filter ought to be replaced every 30-60 days.
- A 2" pleated air filter ought to be swapped out every 3 months.
- A 3” pleated air filter should be switched every 4 months.
- A 4" pleated air filter ought to be swapped out every 6 months.
- A 5” or 6" pleated air filter ought to be swapped every 9-12 months.
One of the benefits of thicker filters is not only do they last longer, but they also have a better MERV Rating. This means they will do a superior job of getting rid of the particles in your home. They also create less air resistance, which can help your HVAC system run more efficiently and reduce strain on components like the blower motor.
If you want a whole-home air purifier, you will also need to exchange the filters more frequently.
How regularly should I change my air filter if I own a dog or cat?
If you have pets, you might need to change out your air filter more regularly. Pet hair and dander can rapidly clog an air filter and lower its effectiveness. For every shedding dog you want, expect to exchange the filter a month sooner than you would in a home lacking 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 need to replace your air filter as much.
Even though it's a good rule of thumb, you might want to examine the air filter more often to determine if it needs to be exchanged. Dogs don't shed the same amount all year. They shed more in the spring and fall when they are blowing their coat. Check the air filter each month and change it when it looks clogged.
Here are averages that can help you learn how regularly you should install a new air filter at your residence:
- Vacation house or one 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 someone has allergies: 20–45 days