How regularly you have to exchange your air filters could depend on the following:
- Air filter type
- 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, companies typically instruct you to change them every 30–90 days. If you suffer from light to moderate allergies, you could install a better air filter or exchange them even more often.
The short answer to "how frequently do I have to switch out the air filter?":
If there isn't 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 before replacing it.
What air filter styles survive longer?
Some air filters are supposed to survive up to six months, while others should be changed month-to-month. The larger the air filter, the longer it can last. Overall, you need to look at the thickness of the filter rather than the brand. You also need to look 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 better the MERV Rating, the smaller the particle that could be caught by your air filter.
While a filter with a higher MERV Rating will last longer, it could also restrict the ventilation in your home. And you will have to change the filter more frequently. And if you have an older system, plan to switch out the filter more often to maintain the quality of your filter.
How often should I replace 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 often than a 4" filter.
- A 1" pleated air filter should be changed out every 30-60 days.
- A 2" pleated air filter ought to be exchanged every 90 days.
- A 3” pleated air filter should be exchanged every 120 days.
- A 4" pleated air filter should be replaced every 6 months.
- A 5” or 6" pleated air filter ought to be replaced every 9-12 months.
One of the advantages of thicker filters is not only do they survive longer, but they also posses a higher MERV Rating. This means they should do a superior job of filtering out the particles inside your home. They also create less air resistance, which can help an HVAC system run more proficiently and decrease wear and tear on components such as the blower motor.
If you want a whole-home air purifier, you will also have to replace the filters more regularly.
How regularly should I replace my air filter if I own a dog or cat?
If you want pets, you might have to replace your air filter more often. Pet hair and dander can rapidly clog an air filter and reduce its effectiveness. For each shedding dog you have, expect to change out the filter a month sooner than you would with a home lacking pets. The same applies to cats, although they tend not to shed as much as dogs. If you own a hypoallergenic or non-shedding dog or cat, you might not have to replace your air filter as much.
Even though it's a good rule of thumb, you might want to check on the air filter more often to decide 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. Take a look at the air filter each month and replace it when it seems clogged.
Here are averages that can help you learn how frequently you should put in a new air filter at your residence:
- Vacation house or an individual occupant and no pets or allergies: every 6–12 months
- Ordinary suburban home without pets: every 3 months
- One dog or cat: every 2 months
- More than one pet or if a member of your family has allergies: 20–45 days