How regularly you have to exchange the air filters may depend on the following:
- Air filter design
- Overall indoor air quality
- Quantity of pets
- Household size
- Air pollution levels and construction around the residence
- The MERV Rating
For standard 1"–3" air filters, brands usually instruct you to change them every 30–90 days. If you suffer from mild to moderate allergies, you can install a better air filter or change them even more often.
The quick answer to "how frequently should I replace the air filter?":
If you don't have a smoker or pets in the 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 before switching it.
What air filter models survive longer?
Many air filters are manufactured to survive up to six months, while others have to be changed month-to-month. The larger the air filter, the longer it can last. Overall, you can check the thickness of the filter as opposed to the brand. You also need to check at the MERV Rating.
The MERV Rating is a scale that stretches from 1-20 and calculates how well an air filter can eliminate particles from the air. The bigger the MERV Rating, the smaller the particle that can be captured by your air filter.
While a filter with a higher MERV Rating should last longer, it can also interfere with the airflow in your home. And you will need to change the filter more frequently. And if you have an older piece of equipment, plan to exchange the filter more frequently to conserve the life of your filter.
How regularly do I need to substitute my air filter based on thickness?
The longevity of an air filter also depends on its thickness. A 1" filter will need to be replaced more frequently than a 4" filter.
- A 1" pleated air filter ought to be replaced every 30-60 days.
- A 2" pleated air filter ought to be exchanged every 90 days.
- A 3” pleated air filter ought to be switched every 4 months.
- A 4" pleated air filter should be exchanged every 6 months.
- A 5” or 6" pleated air filter must be replaced every 9-12 months.
One of the perks of denser filters is not only do they survive longer, but they also have a higher MERV Rating. This means they will do a more effective job of filtering out the particles inside your home. They also generate less air resistance, which can help ones HVAC system run more efficiently and limit wear and tear on components including the blower motor.
If you own a whole-house air purifier, you will also have to switch out the filters more often.
How regularly should I exchange my air filter if I own a dog or cat?
If you have pets, you might need to exchange your air filter more frequently. Pet hair and dander can rapidly clog an air filter and minimize its effectiveness. For each shedding dog you own, expect to replace the filter a month earlier than you would for a home lacking pets. The same goes for cats, although they tend not to shed as often as dogs. If you have a hypoallergenic or non-shedding dog or cat, you might not need to switch out your air filter as much.
Even though it's a good rule of thumb, you will need to check on your air filter more frequently to determine if it needs to be swapped out. Dogs usually do not 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 change it when it looks clogged.
Here are averages that might help you know how often you should get a new air filter at your residence:
- Vacation house or one occupant and no pets or allergies: every 6–12 months
- Common suburban home without pets: every 3 months
- One dog or cat: every 60 days
- More than one pet or if a member of your family has allergies: 20–45 days