How often you should replace your air filters might depend on the following:
- Air filter design
- Total indoor air quality
- Number of pets
- Household size
- Air pollution levels and construction surrounding the residence
- Your MERV Rating
For standard 1"–3" air filters, companies generally tell you to change them every 30–90 days. If you suffer from light to moderate allergies, you can install a better air filter or change them even more often.
The short answer to "how often do I need to replace the air filter?":
If there isn't a smoker or pets in your home, and your filter is the often sold 1" filter with a MERV rating of 4, you should be able to wait up to 90 days before replacing it.
What air filter models survive longer?
Many air filters are manufactured to last 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 need to examine the thickness of the filter versus the brand. You also need to check at the MERV Rating.
The MERV Rating is a scale that goes from 1-20 and measures how efficiently an air filter can eliminate particles from the air. The bigger the MERV Rating, the smaller the particle that will be captured by your air filter.
While a filter with a higher MERV Rating will last longer, it can also restrict the flow of air in your home. And you will need to exchange the filter more frequently. And if you own an older system, plan to substitute the filter more often to preserve the quality of your filter.
How frequently do I need to switch out my air filter based on thickness?
The longevity of an air filter also counts on the thickness. A 1" filter will need to be swapped out more frequently instead of a 4" filter.
- A 1" pleated air filter should be changed out every 30-60 days.
- A 2" pleated air filter must be swapped out every 90 days.
- A 3” pleated air filter must be changed out every 120 days.
- A 4" pleated air filter must 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 boast a higher MERV Rating. This means they will do a better job of eliminating the particles in your home. They also create less air resistance, which can help ones HVAC system work more effectively and cut down on wear and tear on components such as the blower motor.
If you have 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 want a dog or cat?
If you own pets, you might need to exchange your air filter more regularly. Pet hair and dander can quickly clog an air filter and limit its effectiveness. For every shedding dog you own, expect to replace the filter a month earlier than you would for a home lacking pets. The same is true of cats, although they tend not to shed as heavily as dogs. If you have a hypoallergenic or non-shedding dog or cat, you might not have to switch out your air filter as frequently.
Although a good rule of thumb, you might want to examine the air filter more frequently to see if it should be exchanged. Dogs tend not to shed the same amount year-round. They shed more in the spring and fall when they are blowing their coat. Take a look at the air filter every month and change it when it looks clogged.
Here are averages that may help you know how often you should install a new air filter at your residence:
- Vacation house or a single occupant and no pets or allergies: every 6–12 months
- Ordinary suburban home without pets: every 90 days
- A single dog or cat: every 60 days
- More than one pet or if somebody has allergies: 20–45 days