How often you need to replace the air filters could be on the following:
- Air filter design
- Overall indoor air quality
- Quantity of pets
- Household size
- Air pollution levels and construction near the residence
- The MERV Rating
For basic 1"–3" air filters, brands generally tell you to change them every 30–90 days. If someone in your family suffers from light to moderate allergies, you can use a better air filter or exchange them even more often.
The short answer to "how often should I switch out the air filter?":
If you don't have a smoker or pets in the 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 types survive longer?
Some air filters are manufactured to survive up to six months, while others have to be changed monthly. The thicker the air filter, the longer it can last. In most cases, you need to check the thickness of the filter as opposed to the brand. You also need to consider at the MERV Rating.
The MERV Rating is a scale that stretches from 1-20 and calculates how well an air filter can remove particles out of the air. The higher the MERV Rating, the smaller the particle that can be captured by your air filter.
While a filter with a higher MERV Rating can last longer, it might also hamper the flow of air in your home. And you will have to change the filter more often. And if you have an older piece of equipment, plan to substitute the filter more regularly to conserve the life of your filter.
How often do I need to switch out my air filter based on thickness?
The longevity of an air filter also counts on its thickness. A 1" filter will have to be swapped out more frequently versus a 4" filter.
- A 1" pleated air filter must be changed out every 30-60 days.
- A 2" pleated air filter must be switched every 3 months.
- A 3” pleated air filter must be changed out every 4 months.
- A 4" pleated air filter must be replaced every 6 months.
- A 5” or 6" pleated air filter must be changed out every 9-12 months.
One of the perks of denser filters is not only do they last longer, but they also boast a better MERV Rating. This means they can do a better job of filtering out the particles in your home. They also produce less air resistance, which can help your HVAC system function more efficiently and decrease strain on components such as the blower motor.
If you want a whole-house air purifier, you will also have to replace the filters more regularly.
How often should I change my air filter if I want a dog or cat?
If you want pets, you might need to change out your air filter more often. Pet hair and dander can easily clog an air filter and limit its effectiveness. For each shedding dog you want, expect to change out the filter a month earlier than you would with a home without pets. The same applies to cats, although they don't shed as often as dogs. If you want a hypoallergenic or non-shedding dog or cat, you might not have to exchange your air filter as frequently.
Despite being a good rule of thumb, you might want to check the air filter more frequently to decide if it needs to be exchanged. 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 exchange it when it appears clogged.
Here are averages that may help you know how often you should put in a new air filter at your residence:
- Vacation house or one occupant and no pets or allergies: every 6–12 months
- Ordinary suburban home without pets: every 3 months
- A single dog or cat: every 60 days
- More than one pet or if someone has allergies: 20–45 days