How often you need to change the air filters could rely on the following:
- Air filter type
- Total indoor air quality
- Quantity of pets
- Household size
- Air pollution levels and construction near the residence
- Your MERV Rating
For basic 1"–3" air filters, manufacturers generally instruct you to change them every 30–90 days. If you suffer from mild to moderate allergies, you can put in a better air filter or exchange them even more regularly.
The shortest answer to "how frequently should I replace my air filter?":
If you don't have a smoker or pets at 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 prior to changing it.
What air filter types last longer?
Some air filters are designed to last up to six months, while others have to be replaced monthly. The thicker the air filter, the longer it can last. In most cases, you need to check the thickness of the filter instead of the brand. You also need to take a look at the MERV Rating.
The MERV Rating is a scale that goes from 1-20 and calculates how well an air filter should remove particles out of the air. The higher the MERV Rating, the smaller the particle that can be captured by the air filter.
While a filter with a higher MERV Rating will last longer, it might also interfere with the flow of air in your home. And you will need to exchange the filter more often. And if you own an older system, plan to change the filter more often to maintain the quality of your filter.
How regularly do I need to exchange my air filter based on thickness?
The lifespan of an air filter also hinges on its thickness. A 1" filter will have to be swapped out more frequently instead of a 4" filter.
- A 1" pleated air filter must be replaced every 30-60 days.
- A 2" pleated air filter should be switched every 90 days.
- A 3” pleated air filter should be changed out every 4 months.
- 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 advantages of thicker filters is not only do they live longer, but they also have a better MERV Rating. This means they should do a better job of filtering out the particles inside your home. They also produce less air resistance, which can help your HVAC system run more effectively and decrease strain on components like the blower motor.
If you want a whole-home air purifier, you will also have to replace the filters more often.
How regularly should I exchange my air filter if I own a dog or cat?
If you want pets, you might have to replace your air filter more regularly. Pet hair and dander can rapidly clog an air filter and minimize its effectiveness. For each shedding dog you want, expect to replace the filter a month sooner than you would with a home without pets. The same applies to cats, although they tend not to shed as often as dogs. If you want a hypoallergenic or non-shedding dog or cat, you might not need to switch out your air filter as much.
Although a good rule of thumb, you will need to check the air filter more often to decide if it has to be replaced. 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 monthly and change it when it looks clogged.
Here are averages that might help you understand how regularly 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
- Ordinary suburban home without pets: every 90 days
- A single dog or cat: every 60 days
- More than one pet or if a member of your family has allergies: 20–45 days