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How Often Should You Change Your Furnace Filter?

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I'm hoping someone can settle a dispute between my husband and I. I really just want him to see it in print, then maybe it'll sink in. How often does everyone change their furnace filter during the winter months? He changes ours twice a year and really honestly believes that it is often enough. I say it should be every month during November to April. What do you think? I'll show him all responses.

Thank you.
Sandy from Pittsburgh, PA


Recent Answers

Here are the recent answer to this question.

By realist01/12/2015

Keep in mind: It is a complete myth that when a partially clogged filter begins to slow down the airflow, the fan will "work harder to try to maintain airflow". Fans don't try to maintain airflow. They have no will. In the real world, squirrel cage fans actually work harder when they are moving air freely. If you completely block the airflow, the fan will spin faster because it's easier to just spin the air around in its chamber than to move large quantities of air. It doesn't spin faster because it's "trying harder". There are good reasons to change filters, but saving electrical energy from fan use is simply not one of them.

By Jeff Swanson04/18/2013

It really depends on the type of filter you are using. Some should be changed once a month while others should be changed once every three months. There are also a variety of air filters out there including: HEPA, Ionic, Carbon and UV Light. For more information, check out this article: ... nsurance/change-home-air-filter.aspx

By Patrick L.01/07/2013

There is really no standard on when to change your filters, as people have different HVAC systems? My filters are the 3M Merv12 size 16x20x4 & it cost $35-40 a pop at Amazon. If you change that monthly, or even bi-monthly, it will cost hundreds of dollars a year. Get real.


When I bought my furnace, they told me to change the filter every three months. This past February, the furnace wasn't kicking on. I was about to call a service person, then decided to read the trouble-shooting tips on their website. It said to first change the filter. It was at month 2 at that point, but I changed it. The furnace started working right away. From now on, I will change it every 2 months during the winter.

By guest post 206/19/2010

Sorry, but your husband is right if you use regular filters. Read "The Dirt on Furnace Filters" article in the Washington Post by Jeanne Huber from 1/19/06. As long as the filter isn't so clogged that air flow is restricted, the trapped dirt actually helps the filter trap small particles better!

By Mark S. (Guest Post)01/31/2009

We have aprilaire and we change them every six months. This is a great system and really captures a lot of the dust and dander.

By jeff house (Guest Post)05/03/2008

I do heat & air for a living. I've always been told, change the filter every month.

By Jeffrey P (Guest Post)02/13/2008

Did a bunch of research online and monthly is the consensus. I have a HVAC system and I use the Flanders PrecisionAire 14x30x1 filters. A case of 12 covers you for the year and it's $20.00 at Ace Hardware online. Delivered to your door!! That's a small price to pay for cleaner & healthier air in your home, especially if you have kids like me.

By cece (Guest Post)01/28/2008

I change mine every month.

By Steve [4]01/28/2008

I know this "question" is fairly old but, I subscribe to Consumer Reports and there was a small article in the Dec/07 addition that had ratings for furnace filters. In "their" ratings, they listed the cheapy filters, do next to nothing for filtering. The reusuable filters, (pricey) clean even less than the cheapies. In their tests, the best cleaning filter is made by 3M. It filters extremely well and doesn't restrict airflow (In their words) I loaned my Dad that magazine, so I'm sorry that I don't know the exact name of that 3M filter. I do remember it was around $12 dollars though and they recommend changing the filter once a month. So it could get quite expensive for that particular filter. I still use the Ace Hardware cheepies though and DO change them monthly! Hope this helps!! Steve, Blair, Nebr

By Alan Bowen10/18/2007

I agree with the change the filter every month crowd.
Keep your system clean.
Here's a hint.
I just watch Ace hardware. In the Spring they put filters on sale so I just buy a box or two of filters then.
With no central AC we used seven or eight a year here in Northern Lower Michigan.
Now I have just went back to full time wood heat and that furnace just sit there waiting. It doesn't know when it will ever get to run again. 8>))

By dArv (Guest Post)09/03/2007

I have 4" filters and they are recommended to be changed every 90 days. I always write the date on the front of the filter when installing it so I know when it's due to be replaced.

By Holly (Guest Post)08/29/2007

I work for a heating and air conditioning company and the honest answer is, it depends on what type of filter you have. If you are talking about 1" temporary filters, then yes those should be changed monthly. I have a high efficiency 4" filter and those don't need to be changed but once every 6 months. Hope this helps!

By Ann (Guest Post)10/16/2005

We have always changed ours every month, all 12 months. I don't know if this has anything to do with it, but our system is fairly old and when we had a heating/cooling guy in this summer for a problem, he said our system was in great shape. I know some of our neighbors have replaced theirs several years ago.

By Holly [349]10/14/2005

My husband looks at it monthly and if it needs changing, he replaces it. Some months are full of dust and others, not.

By chml (Guest Post)10/14/2005

Great tip!!!!!

Spray with Endust first. That catches more dust!!!!

By chml (Guest Post)10/13/2005

If you want to waste money on heating your home and save money on filters, listen to him.

Filters are on sale at Busy Beaver for $.49 .

I get ours changed once a month for air conditioning and heating.

By Granylou98 (Guest Post)10/13/2005

We have always changed our furnace at least once a month for the past 38 years we have lived here. The furnace runs a lot cleaner and I don't have to dust as often!

By Louise (Guest Post)10/13/2005

My son works for the School district in Los Angeles ,as a Heating and Air conditioning repairman,keeps their furnaces working for the children and he changes theirs every month because he says it helps to keep down the dust,lint, and hair also helps with allergens.we live in Arizona and it's really dusty here so we bought the kind you wash out and change them every month.

By Barbara Huggins [8]10/13/2005

I have always heard to change the filter monthly. Filters aren't really that expensive when you consider that a clean filter makes the furnace run more efficiently

By Donna [4]10/12/2005

My brother in law is living with us now. He works for a heating/cooling company. He says every month! We have dogs and a cat so it really does help. If you pull the filter out and it is dirty change it!

By Beverly (Guest Post)10/12/2005


By Jo (Guest Post)10/12/2005

Our furnace technician recommends changing the filters every month. We try to change ours at least every 2 months.

By Annie Rios Hill [12]10/12/2005

We change ours lots. We have 2 indoor dogs.
We just like to make sure it is clean. We buy the
cheapies and chnage every month or every other month at least.

By Dee [3]10/12/2005

We change our filters every month, we have two dogs and this seems to work best for us and it also keeps down the amount of dust I see on the furniture.

By (Guest Post)10/12/2005

Get the cleanable, reusable kind and hose them off thoroughly once a month. Reuse & recycle whenever possible.

By (Guest Post)10/11/2005

Filters should be changed every 3 months at a minimum. More frequent filter changes are needed more for AC than heat.

By Sara C [1]10/11/2005

I've been told that you should change your furnace filter every three months and possibly more if your area is extremely dusty. For us, I get the very cheap kind and change them every three months. Some of the better filters are reuseable, but have you seen how dirty they get? Good luck!

By Glenda (Guest Post)10/11/2005

You are correct. The cleaner your air filter is kept the more efficient you furnace will run. Thus you save money on heating and repair bills. If you have natural gas you will want to save every penny you can this coming winter with prices expected to be 70% more than last year.

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