How often you should replace your air filters might rely on the following:
- Air filter style
- Total indoor air quality
- Number of pets
- Household size
- Air pollution levels and construction nearby the residence
- The MERV Rating
For basic 1"–3" air filters, companies usually ask you to swap 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 regularly.
The quick answer to "how frequently do I need to swap my air filter?":
If there isn't a smoker or pets in your 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 replacing it.
What air filter types last longer?
A few air filters are supposed to survive up to six months, while others need to be switched month-to-month. The larger the air filter, the longer it should last. In most cases, you need to check the thickness of the filter versus the brand. You also need to look at the MERV Rating.
The MERV Rating is a scale that records from 1-20 and calculates how efficiently an air filter will remove particles out of the air. The higher the MERV Rating, the smaller the particle that could be captured by the air filter.
While a filter with a higher MERV Rating should last longer, it may also restrict the airflow in your home. And you will have to switch out the filter more often. And if you have an older system, plan to replace the filter more regularly to maintain the life of your filter.
How regularly do I have to 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 frequently versus a 4" filter.
- A 1" pleated air filter ought to be replaced every 30-60 days.
- A 2" pleated air filter ought to be switched every 90 days.
- A 3” pleated air filter ought to be switched every 4 months.
- A 4" pleated air filter ought to be exchanged 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 better MERV Rating. This means they will do a superior job of getting rid of the particles within your home. They also produce less air resistance, which can help an HVAC system run more proficiently and decrease strain on components such as the blower motor.
If you have a whole-house air purifier, you will also need to exchange the filters more often.
How often should I exchange my air filter if I have a dog or cat?
If you have pets, you might need to change out your air filter more frequently. Pet hair and dander can quickly clog an air filter and lower its effectiveness. For each shedding dog you have, expect to exchange the filter a month sooner than you would in 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 have to exchange your air filter as much.
Even though it's a good rule of thumb, you might want to examine the air filter more regularly to decide if it needs to be swapped out. Dogs usually do not shed at the same rate all year. They shed more in the spring and fall when they are blowing their coat. Check the air filter monthly and change it when it appears clogged.
Here are averages that can help you know how often you should put in 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
- One dog or cat: every 2 months
- More than one pet or if somebody has allergies: 20–45 days