How regularly you should change the air filters may rely on the following:
- Air filter style
- Overall indoor air quality
- Quantity of pets
- Household size
- Air pollution levels and construction around the residence
- Your MERV Rating
For standard 1"–3" air filters, companies generally instruct you to replace them every 30–90 days. If you suffer from mild to moderate allergies, you could install a better air filter or exchange them even more often.
The short answer to "how often do I need to switch out the air filter?":
If you don't have a smoker or pets at home, and your 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 last longer?
Some air filters are designed to survive up to six months, while others need to be replaced monthly. The thicker the air filter, the longer it can last. In general, you need to look at the thickness of the filter rather than the brand. You also need to check at the MERV Rating.
The MERV Rating is a scale that records from 1-20 and calculates how well an air filter can eliminate particles from the air. The better the MERV Rating, the smaller the particle that will be captured by your air filter.
While a filter with a higher MERV Rating might last longer, it might also impede the ventilation in your home. And you will need to switch out the filter more often. And if you acquire an older piece of equipment, plan to switch out the filter more frequently to preserve the quality of your filter.
How regularly do I have to substitute my air filter based on thickness?
The longevity of an air filter also depends on its thickness. A 1" filter will have to be exchanged more frequently instead of a 4" filter.
- A 1" pleated air filter ought to be changed every 30-60 days.
- A 2" pleated air filter ought to be exchanged every 90 days.
- A 3” pleated air filter must be changed out every 120 days.
- A 4" pleated air filter should be replaced every 6 months.
- A 5” or 6" pleated air filter must be swapped every 9-12 months.
One of the advantages of thicker filters is not only do they survive longer, but they also posses a higher MERV Rating. This means they should do a better job of getting rid of the particles inside your home. They also generate less air resistance, which can help ones HVAC system work more proficiently and decrease wear and tear on components including the blower motor.
If you have a whole-home air purifier, you will also have to replace the filters more regularly.
How regularly should I exchange my air filter if I want a dog or cat?
If you own pets, you might have to switch out your air filter more regularly. Pet hair and dander can rapidly clog an air filter and limit its effectiveness. For each shedding dog you own, expect to change out the filter a month earlier than you would in a home without pets. The same goes for cats, although they tend not to shed as often as dogs. If you own a hypoallergenic or non-shedding dog or cat, you might not need to change out your air filter as frequently.
Despite being a good rule of thumb, you will need to examine your air filter more often to decide if it has to be exchanged. Dogs tend not to shed the same amount all year. They shed more in the spring and fall when they are blowing their coat. Check the air filter every month and change it when it appears clogged.
Here are averages that might help you understand how frequently you should install 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 60 days
- More than one pet or if somebody has allergies: 20–45 days