How frequently you have to replace the air filters could rely on the following:
- Air filter design
- Overall indoor air quality
- Number of pets
- Household size
- Air pollution levels and construction nearby the residence
- The MERV Rating
For common 1"–3" air filters, manufacturers generally tell you to swap them every 30–90 days. If someone in your family suffers from light to moderate allergies, you can install a better air filter or change them even more regularly.
The quick answer to "how often do I need to replace the air filter?":
If there isn't a smoker or pets in the home, and the 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 survive longer?
Some air filters are manufactured to survive up to six months, while others need to be switched each month. The thicker the air filter, the longer it can last. In most cases, you should 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 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 captured by the air filter.
While a filter with a higher MERV Rating might last longer, it might also impede 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 exchange 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 often instead of a 4" filter.
- A 1" pleated air filter should be changed every 30-60 days.
- A 2" pleated air filter must be switched every 90 days.
- A 3” pleated air filter should be replaced 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 perks of thicker filters is not only do they live longer, but they also posses a higher MERV Rating. This means they will do a better job of filtering out the particles within your home. They also generate less air resistance, which can help your HVAC system function more effectively and reduce strain on components such as the blower motor.
If you have a whole-house air purifier, you will also have to replace the filters more often.
How often should I exchange my air filter if I own a dog or cat?
If you own pets, you might have to change out your air filter more often. Pet hair and dander can rapidly clog an air filter and minimize its effectiveness. For every shedding dog you have, expect to switch out the filter a month sooner than you would in a home without pets. The same goes for cats, although they usually do not shed as heavily as dogs. If you own a hypoallergenic or non-shedding dog or cat, you might not need to exchange your air filter as often.
Although a good rule of thumb, you will need to check the air filter more often to see if it should be exchanged. Dogs tend not to shed at the same rate all year. They shed more in the spring and fall when they are blowing their coat. Inspect the air filter every month and replace it when it appears clogged.
Here are averages that can help you know how frequently you should get a new air filter at your residence:
- Vacation house or a single occupant and no pets or allergies: every 6–12 months
- Standard suburban home without pets: every 90 days
- One dog or cat: every 60 days
- More than one pet or if someone has allergies: 20–45 days