How often should I change my air filter at home?

How regularly you have to replace your air filters might depend on the following:

Air filter model
Total indoor air quality
Quantity of pets
Household size
Air pollution levels and construction nearby the residence
The MERV Rating

For common 1"–3" air filters, brands usually tell you to swap them every 30–90 days. If someone in your family suffers from light to moderate allergies, you could install a better air filter or exchange them even more often.

The shortest answer to "how frequently should I switch out my air filter?":

If there isn't a smoker or pets in the 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 changing it.

What air filter styles survive longer?

Some air filters are supposed to last up to six months, while others have to be exchanged each month. The larger the air filter, the longer it should last. Generally, you can examine the thickness of the filter versus the brand. You also need to consider at the MERV Rating.

The MERV Rating is a scale that goes from 1-20 and assesses how effectively an air filter should remove 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 can last longer, it might also hamper the circulation in your home. And you will need to exchange the filter more regularly. And if you have an older system, plan to replace the filter more regularly to maintain the quality of your filter.

How regularly 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 have to be swapped out more frequently instead of a 4" filter.

A 1" pleated air filter ought to be replaced every 30-60 days.
A 2" pleated air filter ought to be replaced every 90 days.
A 3” pleated air filter should be replaced every 4 months.
A 4" pleated air filter ought to be exchanged every 6 months.
A 5” or 6" pleated air filter should 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 better MERV Rating. This means they can do a more effective job of filtering out the particles within your home. They also create less air resistance, which can help your HVAC system run more efficiently and decrease wear and tear on components including the blower motor.

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

How regularly should I change my air filter if I want a dog or cat?

If you have pets, you might need to replace your air filter more frequently. Pet hair and dander can rapidly clog an air filter and limit its effectiveness. For every shedding dog you own, expect to switch out the filter a month earlier than you would for a home lacking pets. The same applies to cats, although they tend not to shed as heavily as dogs. If you want a hypoallergenic or non-shedding dog or cat, you might not need to switch out your air filter as frequently.

Even though it's a good rule of thumb, you might want to check on your air filter more regularly to see if it should be replaced. Dogs don't shed the same amount 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 seems clogged.

Here are averages that may help you understand how frequently 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 3 months
One dog or cat: every 60 days
More than one pet or if anyone has allergies: 20–45 days