How often you should replace the air filters may be on the following:
- Air filter design
- Total indoor air quality
- Quantity of pets
- Household size
- Air pollution levels and construction surrounding the residence
- Your MERV Rating
For standard 1"–3" air filters, companies generally instruct you to exchange them every 30–90 days. If someone in your family suffers from mild to moderate allergies, you can install a better air filter or replace them even more frequently.
The short answer to "how often do I need to replace the air filter?":
If there isn't a smoker or pets at home, and the filter is the commonly sold 1" filter with a MERV rating of 4, you should be able to wait up to 90 days prior to switching it.
What air filter styles last longer?
Many air filters are supposed to last up to six months, while others should be swapped month-to-month. The denser the air filter, the longer it can last. Generally, you should check the thickness of the filter instead of 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 well an air filter can eliminate particles out of the air. The better the MERV Rating, the smaller the particle that can be captured by the air filter.
While a filter with a higher MERV Rating might last longer, it can also interfere with the flow of air in your home. And you will have to replace the filter more often. And if you have an older system, plan to change the filter more regularly to preserve the life of your filter.
How regularly should I exchange my air filter based on thickness?
The longevity of an air filter also relies on its thickness. A 1" filter will have to be changed out more often than a 4" filter.
- A 1" pleated air filter ought to be exchanged every 30-60 days.
- A 2" pleated air filter must be replaced every 90 days.
- A 3” pleated air filter should be replaced every 120 days.
- A 4" pleated air filter ought to be swapped out every 6 months.
- A 5” or 6" pleated air filter ought to be replaced every 9-12 months.
One of the benefits of thicker filters is not only do they survive longer, but they also posses a higher MERV Rating. This means they will do a more effective job of filtering out the particles within your home. They also produce less air resistance, which can help an HVAC system operate more proficiently and reduce wear and tear on components like the blower motor.
If you want a whole-house air purifier, you will also need to exchange the filters more regularly.
How often should I exchange my air filter if I have a dog or cat?
If you want pets, you might have to switch out your air filter more frequently. Pet hair and dander can rapidly clog an air filter and lower its effectiveness. For each shedding dog you want, expect to exchange the filter a month sooner than you would in a home without pets. The same is true of cats, although they usually do not shed as often as dogs. If you want a hypoallergenic or non-shedding dog or cat, you might not have to change out your air filter as much.
Even though it's a good rule of thumb, you might want to check on the air filter more regularly to figure out if it has to be replaced. Dogs don't shed at the same rate year-round. They shed more in the spring and fall when they are blowing their coat. Take a look at the air filter monthly and change it when it appears clogged.
Here are averages that may help you understand how regularly 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
- Common suburban home without pets: every 3 months
- One dog or cat: every 2 months
- More than one pet or if somebody has allergies: 20–45 days