How often should I change my air filter at home?

How often you need to replace your air filters might depend on the following:

Air filter design
Overall indoor air quality
Quantity of pets
Household size
Air pollution levels and construction nearby the residence
Your MERV Rating

For standard 1"–3" air filters, companies normally ask you to swap them every 30–90 days. If you suffer from light to moderate allergies, you could install a better air filter or exchange them even more frequently.

The quick answer to "how frequently do I have to swap the air filter?":

If you don't have a smoker or pets in your 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 prior to replacing it.

What air filter types survive longer?

Some air filters are supposed to survive up to six months, while others should be replaced monthly. The thicker the air filter, the longer it can last. In general, you should examine the thickness of the filter as opposed to the brand. You also need to look at the MERV Rating.

The MERV Rating is a scale that stretches from 1-20 and calculates how efficiently an air filter can eliminate particles out of 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 will last longer, it might also interfere with the circulation in your home. And you will need to replace the filter more regularly. And if you own an older piece of equipment, plan to substitute the filter more often to conserve the life of your filter.

How frequently do I need to switch out my air filter based on thickness?

The longevity of an air filter also counts on its thickness. A 1" filter will have to be replaced more often than a 4" filter.

A 1" pleated air filter ought to be replaced every 30-60 days.
A 2" pleated air filter should be switched every 90 days.
A 3” pleated air filter should be switched every 120 days.
A 4" pleated air filter ought to be exchanged every 6 months.
A 5” or 6" pleated air filter should be replaced every 9-12 months.

One of the advantages of thicker filters is not only do they live longer, but they also provide a higher MERV Rating. This means they should do a better job of getting rid of the particles within your home. They also produce less air resistance, which can help ones HVAC system work more effectively and decrease wear and tear on components such as the blower motor.

If you have a whole-home air purifier, you will also have to switch out the filters more often.

How often should I change my air filter if I own a dog or cat?

If you have pets, you might have to switch out your air filter more frequently. Pet hair and dander can easily clog an air filter and lower its effectiveness. For every shedding dog you want, expect to switch out the filter a month sooner than you would in a home lacking pets. The same goes for cats, although they usually do not shed as heavily as dogs. If you have a hypoallergenic or non-shedding dog or cat, you might not need to replace your air filter as often.

Despite being a good rule of thumb, you will need to examine your air filter more often to see if it needs to be exchanged. Dogs usually do not shed at the same rate year-round. They shed more in the spring and fall when they are blowing their coat. Take a look at the air filter every month and change it when it looks clogged.

Here are averages that might help you learn how frequently you should get a new air filter at your residence:

Vacation house or one occupant and no pets or allergies: every 6–12 months
Standard suburban home without pets: every 3 months
A single dog or cat: every 2 months
More than one pet or if anyone has allergies: 20–45 days