How often should I change my air filter at home?

change air filter

How regularly you need to change your air filters can rely on the following:

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

For standard 1"–3" air filters, manufacturers typically ask you to change them every 30–90 days. If someone in your family suffers from light to moderate allergies, you could install a better air filter or replace them even more often.

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

If there isn't a smoker or pets in the home, and the 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?

A few air filters are supposed to last up to six months, while others should be changed each month. The larger the air filter, the longer it can last. Overall, you should look at the thickness of the filter as opposed to the brand. You also need to take a 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 higher the MERV Rating, the smaller the particle that will be captured by the air filter.

While a filter with a higher MERV Rating might last longer, it might also restrict the ventilation in your home. And you will need to replace the filter more regularly. And if you own an older system, plan to exchange the filter more frequently to preserve the quality of your filter.

How frequently should I exchange my air filter based on thickness?

The longevity of an air filter also depends on its thickness. A 1" filter will need to be changed out more frequently versus a 4" filter.

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

One of the advantages of thicker filters is not only do they live longer, but they also posses a better MERV Rating. This means they can do a more effective job of getting rid of the particles within your home. They also generate less air resistance, which can help your HVAC system function more efficiently and cut down on wear and tear on components including the blower motor.

If you want a whole-house air purifier, you will also need to exchange the filters more frequently.

How often should I exchange my air filter if I have a dog or cat?

If you have pets, you might need to switch out your air filter more regularly. Pet hair and dander can quickly clog an air filter and minimize its effectiveness. For every shedding dog you have, expect to replace the filter a month sooner than you would in a home without pets. The same applies to cats, although they don't shed as often as dogs. If you own a hypoallergenic or non-shedding dog or cat, you might not need to replace your air filter as frequently.

Even though it's a good rule of thumb, you might want to examine your air filter more regularly to figure out if it has to be replaced. Dogs usually do not shed the same amount all year. They shed more in the spring and fall when they are blowing their coat. Inspect the air filter each month and change it when it looks clogged.

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

  • Vacation house or one 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 someone has allergies: 20–45 days
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