How regularly you need to replace your air filters may depend on the following:
- Air filter type
- Total indoor air quality
- Quantity of pets
- Household size
- Air pollution levels and construction near the residence
- The MERV Rating
For standard 1"–3" air filters, companies typically tell you to exchange them every 30–90 days. If you suffer from mild to moderate allergies, you could put in a better air filter or exchange them even more regularly.
The quick 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 often 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 types last longer?
Many air filters are designed to last up to six months, while others have to be replaced each month. The thicker the air filter, the longer it should last. Overall, you need to examine the thickness of the filter versus the brand. You also need to check at the MERV Rating.
The MERV Rating is a scale that goes from 1-20 and calculates how efficiently an air filter can remove particles from the air. The better 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 may also hamper the flow of air in your home. And you will have to exchange the filter more regularly. And if you own an older system, plan to replace the filter more often to conserve the life of your filter.
How frequently should I switch out my air filter based on thickness?
The longevity of an air filter also depends on the thickness. A 1" filter will need to be changed out more frequently than a 4" filter.
- A 1" pleated air filter should be exchanged every 30-60 days.
- A 2" pleated air filter should be replaced every 3 months.
- A 3” pleated air filter ought to be replaced every 120 days.
- A 4" pleated air filter should be swapped out every 6 months.
- A 5” or 6" pleated air filter ought to be swapped every 9-12 months.
One of the benefits of thicker filters is not only do they live longer, but they also provide a higher MERV Rating. This means they can do a superior job of eliminating the particles inside your home. They also produce less air resistance, which can help an HVAC system work more proficiently and limit wear and tear on components like the blower motor.
If you want a whole-home air purifier, you will also have to switch out the filters more regularly.
How often should I change my air filter if I have a dog or cat?
If you want pets, you might need to replace your air filter more often. Pet hair and dander can quickly clog an air filter and lower its effectiveness. For each shedding dog you have, expect to replace the filter a month earlier than you would for a home with no pets. The same is true of cats, although they don't shed as much as dogs. If you want a hypoallergenic or non-shedding dog or cat, you might not have to change out your air filter as often.
Despite being a good rule of thumb, you will need to check on the air filter more frequently to see if it should be swapped out. Dogs don't shed at the same rate year-round. They shed more in the spring and fall when they are blowing their coat. Inspect the air filter monthly and exchange it when it appears clogged.
Here are averages that might help you understand how often you should get a new air filter at your residence:
- Vacation house or an individual occupant and no pets or allergies: every 6–12 months
- Average suburban home without pets: every 90 days
- A single dog or cat: every 2 months
- More than one pet or if somebody has allergies: 20–45 days