How Often Should Furnace Filters Be Replaced?

A common question that homeowners ask is, “How often should I change my furnace filters?” There are plenty of furnace filter manufacturers that would have you believe that you need to change your air filter every month. While this may be true for anyone with severe allergies or asthma, it’s not necessary for the average homeowner.

We will help you figure out how often you should change your furnace filter in this blog post. We will also discuss why changing your furnace filter is essential.

When To Change Your Air Filter

The general rule of thumb is that you should replace your filter every 90 days. High-quality pleated air filters should be replaced every six months. However, you may need to change your filter more often if your home has more airborne contaminants; airborne particles like smoke, pet dander, and more can build up on your air filter more quickly, reducing your indoor air quality.

furnace filter

If You Smoke Or Someone You Live With Does

If you have smokers in your home, your filter efficiency will decrease.

As your HVAC air filter works to filter out the smoke contaminants from the air, it will become dirty faster. The more smokers you have in your home, the more frequent filter changes you should complete.

The frequency of changes depends on filter sizes. Smaller filters should be swapped to a clean filter once every two months. A thicker disposable filter lasts anywhere from three to six months.


An exceptionally dusty home environment can cause your furnace filter to have a shorter lifespan. More dirt and airborne dust can become trapped in your filter, restricting airflow in your HVAC system.

New filters should be installed every one to two months in a dusty home. This will help keep your furnace running efficiently and will help to improve the air quality in your home.

If You Have A Pet

Pets shed fur that can travel through your HVAC system and into your air filter. So, if you have pets in your home, you may need to change your filters more often. It’s a good idea to check your furnace filters every month and replace them when they are dirty.

Thicker filters are ideal for people with pets because they have more room to collect dust and debris. While you may still need to change air filters more frequently, you will not have to change them as often as someone with a pet and a thinner filter.

inserting furnace air filter

What If I Don’t Change My Air Filter That Often?

More Wear On Your Furnace’s Components

A dirty filter restricts airflow in your heating and cooling system, forcing the blower motor to work harder to draw in the same amount of air. This makes the blower motor wear out much faster than it normally would have. As a result, you may need to have your HVAC equipment serviced more frequently.

If you want to avoid HVAC repair, change your filter every three months to keep your furnace in tip-top shape.

Higher Energy Bills

As previously mentioned, a dirty furnace filter will cause your heating system to work much harder. Your furnace or air conditioner may stay on for a few hours trying to achieve a typical temperature change. This can cause your hydro bill to go up, meaning you’re paying more for your average use.

Changing your air filters frequently can help keep your energy bills low. It only takes a few minutes to switch to a new filter, but it could save you a lot in the long run.

Poor Air Quality

Most furnace filters need to be changed frequently because they are involved in every single heating and cooling cycle, from the furnace to air conditioning.

If you do not change your air filter frequently, then indoor air quality will diminish; all the dirt that is trapped in your old filter will travel through your HVAC system, out of the return air vent, and back into your home—You’re essentially not getting any clean air.

Bad air quality could lead to negative health impacts like breathing difficulties, bad allergies, and asthma. This is especially dangerous for young children.